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 A157808 #4 Aug 24 2025 12:33:10 %S A157808 1,7,12,161,132,847,1332,32977,12612,76657,116052,1401491,1054692, %T A157808 6339067,9533172,459046049,85962372,512834077,774316692,9515828021, %U A157808 6971471652,37110907687,62753730612,2474540324347,564825518532,-11328646894103,5083597438932,2154664585390751 %N A157808 Numerator of Euler(n,4). %t A157808 EulerE[Range[0,30],4]//Numerator (* _Harvey P. Dale_, Aug 24 2025 *) %Y A157808 For denominators see A006519. %K A157808 sign,frac,changed %O A157808 0,2 %A A157808 _N. J. A. Sloane_, Nov 10 2009