A138376 a(n+1) = abs[ a(n) + (-1)^(n+1) * Sum_of_digits_of(n+1)], with a(0)=0.

0, 1, 3, 0, 4, 1, 7, 0, 8, 1, 2, 0, 3, 1, 6, 0, 7, 1, 10, 0, 2, 1, 5, 0, 6, 1, 9, 0, 10, 1, 4, 0, 5, 1, 8, 0, 9, 1, 12, 0, 4, 1, 7, 0, 8, 1, 11, 0, 12, 1, 6, 0, 7, 1, 10, 0, 11, 1, 14, 0, 6, 1, 9, 0, 10, 1, 13, 0, 14, 1, 8, 0, 9, 1, 12, 0, 13, 1, 16, 0, 8, 1, 11, 0, 12, 1, 15, 0, 16, 1, 10, 0, 11, 1, 14

Offset

0,3

Comments

a(4*k)=0, with k>=1

a(4*k-2)=1, with k>=1

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Maple

P:=proc(n) local a, i, k, w; a:=0; print(a); for i from 1 by 1 to n do w:=0; k:=i; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; a:=abs(a+(-1)^i*w); print(a); od; end: P(100);

Mathematica

nxt[{n_, a_}]:={n+1, Abs[a+(-1)^(n+1) Total[IntegerDigits[n+1]]]}; NestList[nxt, {0, 0}, 100][[All, 2]] (* Harvey P. Dale, Jan 04 2019 *)

Crossrefs

Cf. A037123.

Sequence in context: A325491 A306803 A319974 * A077140 A003815 A306562

Adjacent sequences: A138373 A138374 A138375 * A138377 A138378 A138379

Keyword

easy,nonn,base

Author

Paolo P. Lava and Giorgio Balzarotti, May 08 2008

Extensions

Definition corrected by N. J. A. Sloane, Jan 04 2019

Status

approved