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A253602
Numbers n such that the smallest exponent k for n and n^k to have common digits is 4.
2
22, 47, 92, 157, 187, 188, 192, 552, 558, 577, 707, 772, 922, 2522, 8338, 17177, 66888, 575757, 929522, 1717177, 8888588
OFFSET
1,1
EXAMPLE
22^2=484 and 22^3=10648 have no digits in common with 22, but 22^4=234256 has some, so 22 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) == 4;
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Michel Marcus, Jan 05 2015
STATUS
approved