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A072566
Numbers n such that n and sigma(n) end with the same digit in base 10.
4
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
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
KEYWORD
base,nonn
AUTHOR
Benoit Cloitre, Aug 06 2002
STATUS
approved