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A253601
Numbers such that the smallest exponent for n and n^k to have common digits is 3.
3
4, 9, 17, 18, 24, 29, 33, 34, 38, 39, 44, 54, 57, 58, 59, 62, 67, 72, 79, 84, 88, 94, 144, 158, 173, 194, 209, 212, 224, 237, 238, 244, 247, 253, 257, 259, 307, 313, 314, 333, 334, 338, 349, 353, 359, 377, 388, 404, 409, 424, 437, 444, 447, 449, 454, 459, 467
OFFSET
1,1
EXAMPLE
4^2=16 has no digits in common with 4, but 4^3=64 has some, so 4 is in the sequence.
PROG
(PARI) a253600(n) = {sd = Set(vecsort(digits(n))); k=2; while (#setintersect(sd, Set(vecsort(digits(n^k)))) == 0, k++); k; }
isok(n) = a253600(n) == 3;
(PARI) is(n) = my(d(k)=Set(digits(n^k))); !#setintersect(d(1), d(2)) && #setintersect(d(1), d(3)) \\ Iain Fox, Aug 07 2018
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Michel Marcus, Jan 05 2015
STATUS
approved