A072566 Numbers n such that n and sigma(n) end with the same digit in base 10.

1, 14, 34, 40, 44, 74, 78, 81, 84, 94, 120, 124, 134, 138, 164, 190, 194, 198, 204, 214, 224, 244, 254, 258, 270, 274, 280, 284, 290, 294, 314, 318, 334, 360, 361, 364, 380, 394, 404, 438, 440, 441, 444, 454, 462, 498, 514, 520, 524, 528, 540, 544, 554, 558

Offset

1,2

Links

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

Formula

Probably lim n -> infinity a(n)/n = 10.

Maple

filter:= n -> numtheory:-sigma(n)-n mod 10 = 0:
select(filter, [$1..1000]); # Robert Israel, Feb 28 2020

Mathematica

Select[Range[600], Mod[#, 10]==Mod[DivisorSigma[1, #], 10]&] (* Harvey P. Dale, Mar 07 2024 *)

Prog

(PARI) isok(n) = (n % 10) == (sigma(n) % 10); \\ Michel Marcus, Nov 26 2013

Crossrefs

Cf. A000203. Includes 2*n for n in A030432, and n^2 for n in A030433.

Sequence in context: A158899 A085777 A329062 * A039449 A120875 A103533

Adjacent sequences: A072563 A072564 A072565 * A072567 A072568 A072569

Keyword

base,nonn

Author

Benoit Cloitre, Aug 06 2002

Status

approved