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.
%I A382132 #19 Mar 25 2025 18:01:53
%S A382132 6,51,106,141,226,391,526,681,766,951,1501,1891,2031,2326,2481,2641,
%T A382132 3151,3901,4101,4306,6631,6891,7981,8266,8851,10081,10401,11391,13141,
%U A382132 14631,15406,16201,20931,22801,23281,24751,27301,27826,28891,29431,30526,32206,33351,35701,36301,38131,38751
%N A382132 Centered pentagonal numbers which are semiprimes.
%e A382132 A005891(1) = 6 = (5*1^2 + 5*1 + 2)/2 = 2*3.
%e A382132 A005891(4) = 51 = (5*4^2 + 5*4 + 2)/2 = 3*17.
%e A382132 A005891(6) = 106 = (5*6^2 + 5*6 + 2)/2 = 2*53.
%t A382132 Select[Table[(5*n^2 + 5*n + 2)/2, {n, 1, 125}], PrimeOmega[#] == 2 &] (* _Amiram Eldar_, Mar 17 2025 *)
%Y A382132 Intersection of A001358 and A005891.
%Y A382132 Cf. A364610.
%K A382132 nonn
%O A382132 1,1
%A A382132 _Massimo Kofler_, Mar 17 2025