cp's OEIS Frontend

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.

A257692 Numbers such that the smallest nonzero digit present (A257679) in their factorial base representation is 2.

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%I A257692 #19 Feb 14 2024 01:05:25
%S A257692 4,12,16,22,48,52,60,64,66,70,76,84,88,94,100,108,112,118,240,244,252,
%T A257692 256,258,262,288,292,300,304,306,310,312,316,324,328,330,334,336,340,
%U A257692 348,352,354,358,364,372,376,382,408,412,420,424,426,430,436,444,448,454,460,468,472,478,484,492,496,502
%N A257692 Numbers such that the smallest nonzero digit present (A257679) in their factorial base representation is 2.
%C A257692 Numbers k for which A257679(k) = 2.
%H A257692 Antti Karttunen, <a href="/A257692/b257692.txt">Table of n, a(n) for n = 1..10000</a>
%H A257692 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a>.
%e A257692 Factorial base representation (A007623) of 22 is "320" as 22 = 3*3! + 2*2! + 0*1!, thus a(22) = 2.
%t A257692 q[n_] := Module[{k = n, m = 2, r, s = {}}, While[{k, r} = QuotientRemainder[k, m]; k != 0|| r != 0, AppendTo[s, r]; m++]; !MemberQ[s, 1] && MemberQ[s, 2]]; Select[Range[500], q] (* _Amiram Eldar_, Feb 14 2024 *)
%o A257692 (Scheme, with _Antti Karttunen_'s IntSeq-library)
%o A257692 (define A257692 (MATCHING-POS 1 1 (lambda (n) (= 2 (A257679 n)))))
%o A257692 (Python)
%o A257692 def A(n, p=2): return n if n<p else A(n//p, p+1)*10 + n%p
%o A257692 def a(n): return 0 if n==0 else min([int(i) for i in str(A(n)) if i !='0'])
%o A257692 print([n for n in range(1, 503) if a(n)==2]) # _Indranil Ghosh_, Jun 19 2017
%Y A257692 Row 2 of A257503.
%Y A257692 Cf. A007623, A257679, A257693.
%Y A257692 Cf. also A257262.
%K A257692 nonn,base
%O A257692 1,1
%A A257692 _Antti Karttunen_, May 04 2015