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 A262054 #32 Aug 25 2019 05:58:02
%S A262054 25,325,703,817,1825,2101,2353,2465,3277,4525,6697,8321,10225,11041,
%T A262054 11521,12025,13665,14089,19345,20197,20417,20425,25829,29857,29891,
%U A262054 35425,38081,39331,46657,49241,49321,50881,58825,64681,75241,75361,76627,78937,79381
%N A262054 Euler pseudoprimes to base 7: composite integers such that abs(7^((n - 1)/2)) == 1 mod n.
%H A262054 Amiram Eldar, <a href="/A262054/b262054.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..61 from Daniel Lignon)
%t A262054 eulerPseudoQ[n_?PrimeQ, b_] = False; eulerPseudoQ[n_, b_] := Block[{p = PowerMod[b, (n - 1)/2, n]}, p == Mod[1, n] || p == Mod[-1, n]]; Select[2 Range[25000] + 1, eulerPseudoQ[#, 7] &] (* _Michael De Vlieger_, Sep 09 2015, after _Jean-François Alcover_ at A006970 *)
%o A262054 (PARI) for(n=1, 1e5, if( Mod(7, (2*n+1))^n == 1 || Mod(7, (2*n+1))^n == 2*n && bigomega(2*n+1) != 1 , print1(2*n+1", "))); \\ _Altug Alkan_, Oct 11 2015
%Y A262054 Cf. A006970 (base 2), A262051 (base 3), A262052 (base 5), A262053 (base 6), this sequence (base 7), A262055 (base 8).
%K A262054 nonn
%O A262054 1,1
%A A262054 _Daniel Lignon_, Sep 09 2015