login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A261874 Numbers n such that the sum of digits of n is divisible by at least one prime divisor of n. 1
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 (list; graph; refs; listen; history; text; internal format)
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 * A008816 A002271 A048381

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 9 13:57 EDT 2020. Contains 336323 sequences. (Running on oeis4.)