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 A113525 #14 Oct 09 2022 05:20:55 %S A113525 4,49,301,589,973,2353,2701,3073,4333,5293,5809,6349,6913,7501,8749, %T A113525 9409,10801,11533,13069,14701,15553,16429,23233,24301,25393,27649, %U A113525 30001 %N A113525 Semiprimes in A056107. %C A113525 Intersection of A056107 and A001358. %H A113525 Michael De Vlieger, <a href="/A113525/b113525.txt">Table of n, a(n) for n = 1..10000</a> %e A113525 a(1) = 4 because A056107(1) = 3*1^2 + 1 = 4 = 2^2 is semiprime. %e A113525 a(16) = 9409 because A056107(56) = 3*56^2 + 1 = 9409 = 97^2 is semiprime. %e A113525 a(27) = 30001 because A056107(100) = 3*100^2 + 1 = 30001 = 19 * 1579 is semiprime. %t A113525 Select[Array[3 #^2 + 1 &, 100], PrimeOmega[#] == 2 &] (* _Michael De Vlieger_, Mar 17 2021 *) %Y A113525 Cf. A001358, A056107. %Y A113525 Cf. A113519, A113524, A113527, A113528, A113530. %K A113525 easy,nonn %O A113525 1,1 %A A113525 _Jonathan Vos Post_, Jan 12 2006