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 A382217 #9 Mar 20 2025 09:29:17 %S A382217 1,1,1,4,5,1,1,1,1,1,1,4,4,5,5,16,17,18,19,20,21,22,23,1,1,1,1,1,1,1, %T A382217 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,4,4,4,4,4,4,5,5,5,5,5,5,16,16,17, %U A382217 17,64,65,66,67,68,69,70,71,18,18,19,19,76,77,20 %N A382217 a(n) is the least k > 0 such that the factorial base expansion of n starts with that of k. %H A382217 Rémy Sigrist, <a href="/A382217/b382217.txt">Table of n, a(n) for n = 1..10000</a> %H A382217 Rémy Sigrist, <a href="/A382217/a382217.gp.txt">PARI program</a> %H A382217 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a> %F A382217 a(n) = 1 iff n belongs to A265334. %F A382217 a(n) <= A382184(n). %F A382217 a(n) = n iff n belongs to A382218. %e A382217 The first terms, in decimal and in factorial base, are: %e A382217 n a(n) fact(n) fact(a(n)) %e A382217 -- ---- ------- ---------- %e A382217 1 1 1 1 %e A382217 2 1 1,0 1 %e A382217 3 1 1,1 1 %e A382217 4 4 2,0 2,0 %e A382217 5 5 2,1 2,1 %e A382217 6 1 1,0,0 1 %e A382217 7 1 1,0,1 1 %e A382217 8 1 1,1,0 1 %e A382217 9 1 1,1,1 1 %e A382217 10 1 1,2,0 1 %e A382217 11 1 1,2,1 1 %e A382217 12 4 2,0,0 2,0 %e A382217 13 4 2,0,1 2,0 %e A382217 14 5 2,1,0 2,1 %e A382217 15 5 2,1,1 2,1 %o A382217 (PARI) \\ See Links section. %Y A382217 Cf. A000030, A265334, A382184, A382218 (fixed points). %K A382217 nonn,base %O A382217 1,4 %A A382217 _Rémy Sigrist_, Mar 19 2025