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 A116039 #15 Jul 15 2021 10:16:58 %S A116039 1,2,8,9,11,12,18,19,22,23,26,29,33,35,43,47,50,53,57,59,61,69,75,76, %T A116039 77,78,81,89,103,105,109,112,124,125,131,135,140,141,142,143,146,151, %U A116039 153,155,160,166,170,175,176,177,181,189,209,211,215,216,220,225,226 %N A116039 Numbers k such that k + prime(k) + prime(prime(k)) is a semiprime (A001358). %H A116039 Robert Israel, <a href="/A116039/b116039.txt">Table of n, a(n) for n = 1..10000</a> %e A116039 112 is in the sequence since 112 + prime(112) + prime(prime(112)) = 5242 = 2*2621. %p A116039 with(numtheory): A116039:=n->`if`(bigomega(n+ithprime(n)+ithprime(ithprime(n))) = 2, n, NULL): seq(A116039(n), n=1..500); # _Wesley Ivan Hurt_, Jun 23 2015 %Y A116039 Cf. A001358, A116038. %K A116039 nonn %O A116039 1,2 %A A116039 _Giovanni Resta_, Feb 13 2006