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 A293624 #8 May 31 2020 02:12:38 %S A293624 24301222105,34200607741,194305088689,7362505969365,19702357790989, %T A293624 2985533798982149,6091629437910701,24781034010920641, %U A293624 98129837465651129,99860491537987361,105697961209955269,154533752639483489,406611602100644641,714567498159333701 %N A293624 Fermat pseudoprimes to base 2 that are square pyramidal numbers. %C A293624 Rotkiewicz proved that under Schinzel's Hypothesis H this sequence is infinite. %C A293624 Intersection of A001567 and A000330. %C A293624 The corresponding indices of A000330 are 4177, 4681, 8353, 28057, 38953, 207673, 263401, 420481, 665233, 669121, 681913, 773953, ... %H A293624 Amiram Eldar, <a href="/A293624/b293624.txt">Table of n, a(n) for n = 1..10000</a> %H A293624 Andrzej Rotkiewicz, <a href="http://gdz.sub.uni-goettingen.de/dms/load/mod/?PPN=PPN378850199_0028&DMDID=DMDLOG_0007">On pyramidal numbers of order 4</a>, Elemente der Mathematik, Vol. 28 (1973), pp. 14-16. %H A293624 Wikipedia, <a href="https://en.wikipedia.org/wiki/Schinzel%27s_hypothesis_H">Schinzel's Hypothesis H</a>. %t A293624 p[n_]:=n(n+1)(2n+1)/6; Select[p[Range[3, 10^6]],PowerMod[2,(#-1),#] == 1 &] %Y A293624 Cf. A000330, A001567, A293625. %K A293624 nonn %O A293624 1,1 %A A293624 _Amiram Eldar_, Oct 13 2017