OFFSET
1,1
EXAMPLE
a(4) = 21 because 21 is the smallest odd k > 1 which is Niven in bases 1 (trivial), 2, 3, and 4, being equal to (10101)_2, (210)_3 and (111)_4.
MATHEMATICA
a[n_] := Block[{k=3}, n > 1 && While[Max@ Mod[k, Total /@ IntegerDigits[k, Range[2, n]]] > 0, k += 2]; k]; Array[a, 9]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Jun 03 2013
STATUS
approved