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 A377841 #25 Dec 10 2024 10:15:09 %S A377841 1,2,13,4,8,6,37,14,49,10,20,12,1553,26,85,16,97,18,47,32,15114,22,44, %T A377841 89,145,50,54,28,56,30,33,187,31,4073,68,36,122,91,76,40,80,42,61,86, %U A377841 265,46,277,94,289,98,205,52,62,1260,337,63,971,58,349,60,288,167,84,379,128 %N A377841 Index of first occurrence of n in A375277, or -1 if n does not appear there. %t A377841 f[n_] := Mod[n!, NextPrime@ n]; t[_] := 0; k = 0; While[k < 15201, a = f@ k; If[ t[a] == 0, t[a] = k]; k++]; t /@ Range[0, 70] %Y A377841 Cf. A000040, A000142, A375277. %K A377841 base,nonn %O A377841 1,2 %A A377841 _Robert G. Wilson v_, Nov 10 2024