A217578 a(n) is the least multiple of n, greater than n, such that all digits of a(n) are even (resp. odd) if n is even (resp. odd).

3, 4, 9, 8, 15, 24, 35, 24, 99, 20, 33, 24, 39, 28, 75, 48, 51, 288, 57, 40, 315, 44, 115, 48, 75, 208, 135, 84, 319, 60, 93, 64, 99, 68, 175, 288, 111, 228, 117, 80, 533, 84, 559, 88, 135, 460, 517, 240, 539, 200, 153, 208, 159, 486, 715, 224, 171, 406, 177

Offset

1,1

Comments

Inspired by Problem 300 in Mathematical Excalibur, Vol. 13, No. 1, February-April, 2008.

Links

Michel Marcus, Table of n, a(n) for n = 1..1000

Kin Y. Li, Problem 300, Mathematical Excalibur, Vol. 13, No. 1, February-April, 2008.

Mathematica

Table[k = 2; While[d = IntegerDigits[k*n]; If[OddQ[n], done = And @@ OddQ[d], done = And @@ EvenQ[d]]; ! done, k++]; k*n, {n, 100}] (* T. D. Noe, Oct 09 2012 *)

Prog

(PARI) digs(val, imod2) = {while(val, if ((val%10) % 2 != imod2, return (0)); val = floor(val/10); ); return (1); } digi(i, imod2) = {local(v); v = 2*i; while (! digs(v, imod2), v += i; ); return (v); } digv(n) = {local(i, v); for (i=1, n, v = digi(i, i % 2); print1(v, ", "); ); }

Crossrefs

Sequence in context: A239384 A242219 A106833 * A280616 A317099 A317715

Adjacent sequences: A217575 A217576 A217577 * A217579 A217580 A217581

Keyword

nonn,base

Author

Michel Marcus, Oct 07 2012

Status

approved