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A257693
Numbers such that the smallest nonzero digit present (A257679) in their factorial base representation is 3.
5
18, 72, 90, 114, 360, 378, 432, 450, 456, 474, 498, 552, 570, 594, 618, 672, 690, 714, 2160, 2178, 2232, 2250, 2256, 2274, 2520, 2538, 2592, 2610, 2616, 2634, 2640, 2658, 2712, 2730, 2736, 2754, 2760, 2778, 2832, 2850, 2856, 2874, 2898, 2952, 2970, 2994, 3240, 3258, 3312, 3330, 3336, 3354, 3378, 3432, 3450, 3474, 3498, 3552
OFFSET
1,1
COMMENTS
Numbers k for which A257679(k) = 3.
EXAMPLE
Factorial base representation (A007623) of 18 is "300" (as 18 = 3*3! + 0*2! + 0*1!), thus a(18) = 3.
MATHEMATICA
q[n_] := Module[{k = n, m = 2, r, s = {}}, While[{k, r} = QuotientRemainder[k, m]; k != 0|| r != 0, AppendTo[s, r]; m++]; !ContainsAny[s, {1, 2}] && MemberQ[s, 3]]; Select[Range[3600], q] (* Amiram Eldar, Feb 14 2024 *)
PROG
(Scheme, with Antti Karttunen's IntSeq-library)
(define A257693 (MATCHING-POS 1 1 (lambda (n) (= 3 (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, 4001) if a(n)==3]) # Indranil Ghosh, Jun 19 2017
CROSSREFS
Row 3 of A257503.
Cf. also A257263.
Sequence in context: A059224 A174492 A088490 * A231328 A274577 A347360
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, May 04 2015
STATUS
approved