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A239210 Numbers n such that n^2 is not divisible by any of its nonzero digits. 4
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 (list; graph; refs; listen; history; text; internal format)
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.

MATHEMATICA

ndnzQ[n_]:=Count[n^2/Select[IntegerDigits[n^2], #!=0&], _?IntegerQ]==0; Select[Range[750], ndnzQ] (* Harvey P. Dale, Jun 02 2015 *)

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.

Sequence in context: A087168 A247560 A215824 * A191087 A032454 A107643

Adjacent sequences:  A239207 A239208 A239209 * A239211 A239212 A239213

KEYWORD

nonn,base

AUTHOR

Colin Barker, Mar 12 2014

STATUS

approved

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Last modified July 5 21:00 EDT 2020. Contains 335473 sequences. (Running on oeis4.)