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A257692
Numbers such that the smallest nonzero digit present (A257679) in their factorial base representation is 2.
5
4, 12, 16, 22, 48, 52, 60, 64, 66, 70, 76, 84, 88, 94, 100, 108, 112, 118, 240, 244, 252, 256, 258, 262, 288, 292, 300, 304, 306, 310, 312, 316, 324, 328, 330, 334, 336, 340, 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
OFFSET
1,1
COMMENTS
Numbers k for which A257679(k) = 2.
EXAMPLE
Factorial base representation (A007623) of 22 is "320" as 22 = 3*3! + 2*2! + 0*1!, thus a(22) = 2.
MATHEMATICA
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 *)
PROG
(Scheme, with Antti Karttunen's IntSeq-library)
(define A257692 (MATCHING-POS 1 1 (lambda (n) (= 2 (A257679 n)))))
(Python)
def A(n, p=2): return n if n<p else A(n//p, p+1)*10 + n%p
def a(n): return 0 if n==0 else min([int(i) for i in str(A(n)) if i !='0'])
print([n for n in range(1, 503) if a(n)==2]) # Indranil Ghosh, Jun 19 2017
CROSSREFS
Row 2 of A257503.
Cf. also A257262.
Sequence in context: A081523 A310567 A310568 * A053006 A328849 A261958
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, May 04 2015
STATUS
approved