The On-Line Encyclopedia of Integer Sequences (OEIS)

A239210 revision #8

A239210

Numbers n such that n^2 is not divisible by any of its nonzero digits.

7, 17, 23, 26, 47, 53, 67, 73, 76, 77, 83, 86, 94, 97, 143, 157, 163, 167, 173, 176, 187, 193, 194, 197, 223, 233, 236, 244, 253, 256, 257, 260, 274, 277, 283, 287, 293, 307, 313, 314, 457, 473, 493, 503, 517, 523, 527, 533, 547, 553, 577, 583, 587, 607, 613

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OFFSET

1,1

LINKS

Colin Barker, Table of n, a(n) for n = 1..1000

EXAMPLE

53 is in the sequence because 53^2 = 2809 which is not divisible by 2, 8 or 9.

PROG

(PARI) isOK(n) = my(v=vecsort(digits(n^2), , 8)); for(i=1+(v[1]==0), #v, if(n^2%v[i]==0, return(0))); 1

s=[]; for(n=1, 1000, if(isOK(n), s=concat(s, n))); s

CROSSREFS

Cf. A239211, A239212, A239213.