A077252 - OEIS

A077252

Sum of digits squared minus sum of digits of n.

0, 2, 6, 12, 20, 30, 42, 56, 72, 0, 0, 2, 6, 12, 20, 30, 42, 56, 72, 2, 2, 4, 8, 14, 22, 32, 44, 58, 74, 6, 6, 8, 12, 18, 26, 36, 48, 62, 78, 12, 12, 14, 18, 24, 32, 42, 54, 68, 84, 20, 20, 22, 26, 32, 40, 50, 62, 76, 92, 30, 30, 32, 36, 42, 50, 60, 72, 86, 102, 42, 42, 44, 48, 54

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OFFSET

1,2

COMMENTS

Inspired by A071440. The quasi-periodic function. First several terms are pronic numbers A002378. See also A077253.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

EXAMPLE

a(13)=6 because (1^2+3^2)-(1+3)=6.

MATHEMATICA

sd[n_]:= Module[{idn = IntegerDigits[n]}, Total[idn^2 - idn]]; Array[sd, 80] (* Vincenzo Librandi, Aug 02 2013 *)

CROSSREFS