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A179081 Parity of sum of digits of n. 10
0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

a(n) = A000035(A007953(n));

characteristic function of numbers with an odd sum of digits in their decimal representation:

a(A054684(n)) = 1; a(A054683(n)) = 0;

a(A179083(n)) = a(A179085(n)) = 1;

a(A179082(n)) = a(A179084(n)) = 0.

LINKS

R. Zumkeller, Table of n, a(n) for n = 0..10000

Index entries for characteristic functions

FORMULA

a(n) = if n<10 then (n mod 2) else a([n/10]) XOR (n mod 2).

EXAMPLE

a(789) = (7+8+9) mod 2 = 0;

a(790) = (7+9+0) mod 2 = 0;

a(791) = (7+9+1) mod 2 = 1.

MATHEMATICA

Array[Mod[Total[IntegerDigits[#]], 2]&, 110, 0] (* Harvey P. Dale, Feb 20 2013 *)

PROG

(PARI) a(n) = vecsum(digits(n)) % 2 \\ Jeppe Stig Nielsen, Jan 06 2018

CROSSREFS

Sequence in context: A131734 A134452 A073445 * A113217 A147781 A082446

Adjacent sequences:  A179078 A179079 A179080 * A179082 A179083 A179084

KEYWORD

base,nonn

AUTHOR

Reinhard Zumkeller, Jun 28 2010

STATUS

approved

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Last modified November 21 11:54 EST 2018. Contains 317447 sequences. (Running on oeis4.)