# [seqfan] Re: A128471

Richard Mathar mathar at strw.leidenuniv.nl
Sun Sep 5 14:20:57 CEST 2010

```http://list.seqfan.eu/pipermail/seqfan/2010-September/005951.html
is correct. My humble proposal is to go with

%I A128471
%S A128471 7,37,67,97,127,157,187,217,247,277,307,337,367,397,427,457,487,517,547,
%T A128471 577,607,637,667,697,727,757,787,817,847,877,907,937,967,997,1027,1057,
%U A128471 1087,1117,1147,1177,1207,1237,1267,1297,1327,1357,1387,1417,1447,1477
%N A128471 30*n+7.
%C A128471 30*n+7 -/+ 2 is a multiple of 3 or 5. For n > 0, this number is not prime.
%C A128471 So with the exception of a(0), no a(n) is a member of a twin prime pair.
%H A128471 <a href="http://home.hccnet.nl/a.w.m.van.der.horst/hcc96.txt">Counting Twin Primes</a>
%H A128471 <a href="Sindx_Rea.html#recLCC">Index to sequences with linear recurrences with constant coefficients</a>, signature (2,-1).
%F A128471 a(n) = 2*a(n-1)-a(n-2). [V. Librandri (vincenzo.librandi(AT)tin.it), Sep 05 2010]
%F A128471 G.f. (7+23*x)/(x-1)^2. [R. J. Mathar, Sep 05 2010]
%o A128471 (PARI) A128471(n)={ return(30*n+7) ; }
%o A128471 for(n=0,30,print1(A128471(n)",")) ; /* R. J. Mathar, Sep 05 2010 */
%Y A128471 Adjacent sequences: A128468 A128469 A128470 this_sequence A128472 A128473 A128474
%Y A128471 Sequence in context: A032588 A123084 A123085 this_sequence A168003 A132231 A104915
%K A128471 easy,nonn
%O A128471 0,1
%A A128471 Cino Hilliard (hillcino368(AT)hotmail.com), May 06 2007
%E A128471 Comment clarified by R. Israel, offset set to zero by R. J. Mathar, Sep 05 2010

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