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

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