A261874 - OEIS

A261874

Numbers n such that the sum of digits of n is divisible by at least one prime divisor of n.

2, 3, 4, 5, 6, 7, 8, 9, 12, 15, 18, 20, 21, 22, 24, 26, 27, 28, 30, 33, 36, 39, 40, 42, 44, 45, 46, 48, 50, 51, 54, 55, 57, 60, 62, 63, 64, 66, 68, 69, 70, 72, 75, 77, 78, 80, 81, 82, 84, 86, 87, 88, 90, 93, 96, 99, 102, 105, 108, 110, 111, 112, 114, 116, 117

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OFFSET

1,1

COMMENTS

Sequence is infinite since it contains all positive multiples of 3. - Michel Marcus, Sep 04 2015

n such that gcd(n, A007953(n)) > 1. - Robert Israel, Sep 04 2015

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

The sum of digits of 15 is 6, and 6 is divisible by 3, a divisors of 15.

MAPLE

select(t -> igcd(t, convert(convert(t, base, 10), `+`)) > 1, [$1..1000]); # Robert Israel, Sep 04 2015

MATHEMATICA

fQ[n_] := AnyTrue[First /@ FactorInteger@ n, Divisible[Total@ IntegerDigits@ n, #] &]; Select[Range@ 120, fQ] // Rest (* Michael De Vlieger, Sep 04 2015, Version 10 *)

PROG

(PARI) isok(n) = {sd = sumdigits(n); fordiv(n, d, if (d > 1, if (! (sd % d), return (1))); ); } \\ Michel Marcus, Sep 04 2015

CROSSREFS

Cf. A007953.

Sequence in context: A322002 A107743 A116066 * A334929 A008816 A002271

Adjacent sequences: A261871 A261872 A261873 * A261875 A261876 A261877

KEYWORD

nonn,base,easy

AUTHOR

Giovanni Teofilatto, Sep 04 2015

EXTENSIONS

More terms from Michel Marcus, Sep 04 2015

STATUS

approved