cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A328493 a(n) = (p_n + 1)*q_n - 1; where (p_n, q_n) is the n-th twin prime pair.

This page as a plain text file.
%I A328493 #19 Aug 30 2021 16:15:13
%S A328493 19,41,155,341,929,1805,3659,5255,10505,11771,19181,22649,32579,37055,
%T A328493 39401,52211,57839,73169,79805,97655,121451,176819,187055,213905,
%U A328493 273005,325469,360599,382541,412805,436259,656909,676505,686411,737021,778805,1041419,1066055,1103549,1128905
%N A328493 a(n) = (p_n + 1)*q_n - 1; where (p_n, q_n) is the n-th twin prime pair.
%F A328493 a(n) = A126251(n) - 1. - _Michel Marcus_, Oct 17 2019
%e A328493 For n = 2, the second twin prime pair is (5, 7). So (5 + 1) * 7 - 1 = 41 is the second term.
%t A328493 (#[[1]]+1)#[[2]]-1&/@Select[Partition[Prime[Range[300]],2,1],#[[2]]- #[[1]] == 2&] (* _Harvey P. Dale_, Aug 30 2021 *)
%o A328493 (PARI) my(p = 3); forprime(n=5, 2000, if(n - p == 2, print1((p + 1)*n - 1, ", ")); p=n)
%Y A328493 Cf. A001359, A006512, A126251.
%K A328493 nonn
%O A328493 1,1
%A A328493 _Dimitris Valianatos_, Oct 16 2019