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 A216996 Numbers n such that the digit sum of n*7 is a multiple of 7. 6
 1, 10, 11, 19, 38, 46, 47, 56, 57, 65, 73, 74, 83, 84, 92, 100, 101, 110, 111, 119, 138, 145, 155, 163, 164, 172, 182, 190, 191, 209, 218, 228, 236, 237, 245, 255, 263, 264, 272, 282, 289, 299, 308, 316, 317, 326, 327, 335, 343, 344, 353, 354, 362, 380, 381 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS If n is in the sequence, so are 10*n and 10*n+1. - Robert Israel, Mar 08 2018 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE 7*19 = 133 and 1+3+3=7. MAPLE filter:= n -> convert(convert(7*n, base, 10), `+`) mod 7 = 0: select(filter, [\$1..1000]); # Robert Israel, Mar 08 2018 MATHEMATICA Select[Range[500], Mod[Total[IntegerDigits[7*#]], 7] == 0 &] (* T. D. Noe, Sep 24 2012 *) PROG (JavaScript) function sumarray(arr) { t=0; for (i=0; i

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Last modified September 22 08:23 EDT 2018. Contains 315270 sequences. (Running on oeis4.)