A147827 Minimum number k for which the digital sum of k*n is 7*n.

0, 7, 34, 133, 997, 7999, 13333, 85714, 749986, 1111111, 79999999, 79090909, 499999999, 2923076923, 14285642857, 133333333333, 499999999993, 2352941117647, 11111111111111, 47368421052631, 3499999999999999, 2380947619047619, 25909090909090909, 43478260869565213

Offset

0,2

Links

Chai Wah Wu, Table of n, a(n) for n = 0..27

Maple

P:=proc(i) local j, k, n, ok, w; for n from 0 by 1 to i do j:=-1; ok:=1; while ok=1 do j:=j+1; w:=0; k:=n*j; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; if w=7*n then ok:=0; print(j); fi; od; od; end: P(100);

Prog

(PARI) a(n) = {my(k = 0); while (sumdigits(k*n) != 7*n, k++); k; }; \\ Michel Marcus, Mar 21 2016

Crossrefs

Cf. A147822-A147826, A147828-A147831.

Sequence in context: A120470 A377883 A036423 * A036632 A036639 A036646

Adjacent sequences: A147824 A147825 A147826 * A147828 A147829 A147830

Keyword

easy,nonn,base

Author

Paolo P. Lava and Giorgio Balzarotti, Nov 14 2008

Extensions

Edited by Charles R Greathouse IV, Nov 01 2009

a(9)-a(16) from Donovan Johnson, Sep 16 2012

a(17)-a(23) from Chai Wah Wu, Mar 20 2016

Status

approved