OFFSET
1,1
COMMENTS
Numbers k for which A257679(k) = 3.
LINKS
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)
(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
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, May 04 2015
STATUS
approved