EDITED A000926 (Re: Duplicate hunting cont.)

Maximilian Hasler maximilian.hasler at gmail.com
Tue Dec 4 14:28:14 CET 2007


> http://www.research.att.com/~njas/sequences/?q=id:A093668|id:A000926&fmt=0
> (Same values, both conjectured to be finite)

but IMHO the attribute "full" should not be put in A000926
until this is proven. "fini" is appropriate.
In this sequence it is written: A000926 is a subset of A093668 (but
A093668 could be added in the cross references; on mathworld it is
written that they are identical).
In the other one, the cross-reference is missing.
So I tentatively submit the following EDIT:

%I A000926 M0476 N0176
%S A000926 1,2,3,4,5,6,7,8,9,10,12,13,15,16,18,21,22,24,25,28,30,33,37,40,42,
%T A000926 45,48,57,58,60,70,72,78,85,88,93,102,105,112,120,130,133,165,168,177,
%U A000926 190,210,232,240,253,273,280,312,330,345,357,385,408,462,520,760,840,1320,1365,1848
%N A000926 Euler's "numerus idoneus" (idoneal, or suitable, or
convenient numbers): n such
               that p odd, (p,n) = 1, having unique representation as
x^2 + n y^2,
               x,y >= 0, (x,y) = 1, implies p prime.
%C A000926 Eric Rains (rains(AT)math.ucdavis.edu) has shown (using
Cox, Theorem 3.22) that
               n is suitable iff n cannot be written as ab+bc+ca with
0<a<b<c; this
               implies that A000926 is a subset of A093668.
%C A000926 If an additional term exists it is > 100000000. - Jud
McCranie (j.mccranie(AT)comcast.net),
               Jun 27 2005
%C A000926 As mentioned by Brown, with the given conditions, p is
either prime or a power of
               a prime. - T. D. Noe (noe(AT)sspectra.com), Aug 13 2007
%D A000926 Z. I. Borevich and I. R. Shafarevich, Number Theory.
Academic Press, NY, 1966, pp.
               425-430.
%D A000926 D. Cox, "Primes of Form x^2 + n y^2", Wiley, 1989, p. 61.
%D A000926 G. Frei, Euler's convenient numbers, Math. Intell. Vol. 7
No. 3 (1985), 55-58 and
               64.
%D A000926 O-H. Keller, Ueber die "Numeri idonei" von Euler, Beitraege
Algebra Geom., 16 (1983),
               79-91. [Math. Rev. 85m:11019]
%D A000926 G. B. Mathews, Theory of Numbers, Chelsea, no date, p. 263.
%D A000926 P. Ribenboim, "Galimatias Arithmeticae", in Mathematics
Magazine 71(5) 339 1998
               MAA or, 'My Numbers, My Friends', Chap.11 Springer-Verlag 2000 NY
%D A000926 J. Steinig, On Euler's ideoneal numbers, Elemente Math., 21
(1966), 73-88.
%D A000926 A. Weil, Number theory: an approach through history; from
Hammurapi to Legendre,
               Birkhaeuser, Boston, 1984; see p. 188.
%D A000926 P. Weinberger, Exponents of the class groups of complex
quadratic fields, Acta Arith.,
               22 (1973), 117-124.
%H A000926 K. S. Brown, Mathpages, <a
href="http://www.mathpages.com/home/kmath058.htm">Numeri
               Idonei</a>
%H A000926 M. Waldschmidt, <a
href="http://arXiv.org/abs/math.NT/0312440">Open Diophantine
               problems</a>
%H A000926 E. W. Weisstein, <a
href="http://mathworld.wolfram.com/IdonealNumber.html">Link
               to a section of The World of Mathematics.</a>
%Y A000926 Cf. A014556.
%Y A000926 Identical to A093668, according to the link to "World of
Mathematics".
%Y A000926 Adjacent sequences: A000923 A000924 A000925 this_sequence
A000927 A000928 A000929
%Y A000926 Sequence in context: A033110 A049812 A026501 this_sequence
A093668 A011875 A053433
%K A000926 nonn,fini,nice
%O A000926 1,2
%A A000926 njas
%E A000926 The numbers shown are conjectured to comprise the complete
list. It is known that
               there is at most one further number.
%E A000926 Edited by Maximilian F. Hasler
(maximilian.hasler(AT)gmail.com), Dec 4 2007





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