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A077252 Sum of digits squared minus sum of digits of n. 2
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 (list; graph; refs; listen; history; text; internal format)
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

Cf. A071440, A002378, A077253.

Sequence in context: A034110 A298010 A118373 * A102069 A160938 A160926

Adjacent sequences:  A077249 A077250 A077251 * A077253 A077254 A077255

KEYWORD

nonn,base

AUTHOR

Zak Seidov, Oct 31 2002

STATUS

approved

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Last modified March 26 14:18 EDT 2019. Contains 321497 sequences. (Running on oeis4.)