A136564 = A007523

Maximilian Hasler maximilian.hasler at gmail.com
Sun Mar 30 21:58:59 CEST 2008


Another recently submitted dupe:

%I A136564
%S A136564 3,13,51413,951413,2951413,53562951413,979853562951413
%N A136564 Primes formed by the reversal of the initial digits of the
decimal expansion of Pi.
%C A136564 The next term consists of the decimal reversal of first 712
digits of Pi (PARI pseudo prime).
%e A136564 51413 is in the list because it is prime and its decimal
reversal, 31415, is the first 5 digits of Pi.
%Y A136564 Cf. A005042.
%K A136564 base,nonn
%O A136564 1,1
%A A136564 Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jan 06 2008

which of course already existed:

%I A007523 M2966
%S A007523 3,13,51413,951413,2951413,53562951413,979853562951413
%N A007523 Primes in (decimal expansion of pi written backwards).
%D A007523 M. Gardner, Whys and Wherefores, Univ. Chicago Press, 1989, p. 84.
%K A007523 base,nonn
%O A007523 1,1
%A A007523 njas, Robert G. Wilson v (rgwv(AT)rgwv.com)
%E A007523 Next terms is a 712-digit strong pseudo-prime (GP-PARI)
beginning 2116599102453...
               and ending ...62648323979853562951413.

However,
1/ the link to A005042 is a good idea
2/ one might also add mutual xrefs to:
 A092845, A011545:

%S A092845 3,13,413,1413,51413,951413,2951413,62951413,562951413,3562951413,
%N A092845 A011545(n) reversed.

3/ it also might be better to change the %E into %C, correct spelling
(terms>term), and replace GP/PARI with the name of the algorithm (PARI
provides different choices for PRP tests, the default is
Baillie-Pomerance-Selfridge-Wagstaff, cf. PARI documentation).
And although it "certainly" prime, unless this is proved one might
prefer a formulation like "Next term is probably A092845(711), ..."
(unless fixing %O A092845 0,1  to 1,1)

Maximilian





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