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 A352997 #18 Apr 19 2022 09:24:28 %S A352997 4,9,18,20,24,25,30,42,49,50,57,65,66,69,70,75,76,78,80,85,93,96,98, %T A352997 99,102,104,110,112,114,121,129,133,141,145,152,153,169,177,186,189, %U A352997 190,192,198,213,217,228,238,242,249,252,258,261,266,272,273,275,282,286,289,290,292,294,297,305,309 %N A352997 Numbers k such that A352996(k) is prime. %C A352997 Numbers k such that the k-th triangular number mod the sum (with multiplicity) of prime factors of k is prime. %C A352997 Contains p^2 for prime p. %H A352997 Robert Israel, <a href="/A352997/b352997.txt">Table of n, a(n) for n = 1..10000</a> %e A352997 a(3) = 18 is a term because A352996(18) = A000217(18) mod A001414(18) = 171 mod 8 = 3 is prime. %p A352997 filter:= proc(n) local t; isprime((n*(n+1)/2) mod add(t[1]*t[2],t=ifactors(n)[2])) end proc: %p A352997 select(filter, [$2..500]); %t A352997 Select[Range[300], PrimeQ[Mod[#*(# + 1)/2, Plus @@ Times @@@ FactorInteger[#]]] &] (* _Amiram Eldar_, Apr 14 2022 *) %Y A352997 Cf. A000217, A001414, A352996. %K A352997 nonn %O A352997 1,1 %A A352997 _J. M. Bergot_ and _Robert Israel_, Apr 14 2022