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A072566 Numbers n such that n and sigma(n) end with the same digit in base 10. 3

%I

%S 1,14,34,40,44,74,78,81,84,94,120,124,134,138,164,190,194,198,204,214,

%T 224,244,254,258,270,274,280,284,290,294,314,318,334,360,361,364,380,

%U 394,404,438,440,441,444,454,462,498,514,520,524,528,540,544,554,558

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

%H Robert Israel, <a href="/A072566/b072566.txt">Table of n, a(n) for n = 1..10000</a>

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

%p filter:= n -> numtheory:-sigma(n)-n mod 10 = 0:

%p select(filter, [$1..1000]); # _Robert Israel_, Feb 28 2020

%o (PARI) isok(n) = (n % 10) == (sigma(n) % 10); \\ _Michel Marcus_, Nov 26 2013

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

%K base,nonn

%O 1,2

%A _Benoit Cloitre_, Aug 06 2002

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Last modified March 29 14:58 EDT 2020. Contains 333107 sequences. (Running on oeis4.)