A078250 - OEIS

A078250

a(1) = 1, a(n) = smallest multiple of n using prime digits if n is composite else smallest multiple of n using composite digits, with a(n) = 0 if there are none.

1, 4, 6, 32, 40, 72, 49, 32, 27, 0, 44, 72, 468, 252, 75, 32, 68, 72, 494, 0, 252, 22, 46, 72, 25, 52, 27, 252, 406, 0, 496, 32, 33, 272, 35, 72, 444, 532, 273, 0, 984, 252, 86, 352, 225, 322, 94, 2352, 735, 0, 255, 52, 689, 2322, 55, 2352, 57, 232, 649, 0

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OFFSET

1,2

COMMENTS

Besides multiples of 10, 625 and its odd multiples have a(n)=0. Based on comment by Robert Israel in A078239. - Andrew Howroyd, Sep 17 2024

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..10000

PROG

(PARI) a(n)={if(n%10==0||n%1250==625, 0, if(n==1, 1, my(S=Set([2, 3, 5, 7])); forstep(m=n, oo, n, my(d=digits(m)); if(0 == #if(isprime(n), select(t->t==1||setsearch(S, t), d), select(t->!setsearch(S, t), d)), return(m)))))} \\ Andrew Howroyd, Sep 17 2024

CROSSREFS

Cf. A074162, A078239, A078240.

Sequence in context: A192083 A068720 A068402 * A239224 A087299 A229712

Adjacent sequences: A078247 A078248 A078249 * A078251 A078252 A078253

KEYWORD

base,easy,nonn

AUTHOR

Amarnath Murthy, Nov 24 2002

EXTENSIONS

a(13) corrected and a(29) onwards from Andrew Howroyd, Sep 17 2024

STATUS

approved