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.

A367792 Centered 10-gonal numbers which are products of two primes.

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%I A367792 #12 Dec 23 2023 20:25:58
%S A367792 361,451,551,781,1711,2101,2761,3781,4061,4351,5611,5951,7031,7801,
%T A367792 8201,8611,9031,10351,10811,11281,11761,12751,13261,14311,15961,16531,
%U A367792 17111,17701,21451,23461,26281,28501,29261,30031,30811,34861,35701,40951,41861,42781,45601,46561
%N A367792 Centered 10-gonal numbers which are products of two primes.
%e A367792 A062786(9) = 361 = 5 * 9 * (9-1) + 1 = 19 * 19.
%e A367792 A062786(10) = 451 = 5 * 10 * (10-1) + 1 = 11 * 41.
%e A367792 A062786(11) = 551 = 5 * 11 * (11-1) + 1 = 19 * 29.
%t A367792 Select[Table[5*n*(n-1) + 1, {n, 1, 100}], PrimeOmega[#] == 2 &] (* _Amiram Eldar_, Nov 30 2023 *)
%Y A367792 Intersection of A062786 and A001358.
%K A367792 nonn
%O A367792 1,1
%A A367792 _Massimo Kofler_, Nov 30 2023