A153639 Evilness of triangular numbers.

1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1

Offset

0,1

Comments

The evilness of a number is 1 if the number is evil and 0 otherwise. The number is evil if it has an even number of ones in its binary expansion.

Links

Table of n, a(n) for n=0..104.

Mathematica

od[n_] := Mod[Count[IntegerDigits[n, 2], 1], 2] Table[1 - od[n (n + 1)/2], {n, 0, 128}]
If[EvenQ[DigitCount[#, 2, 1]], 1, 0]&/@Accumulate[Range[0, 110]] (* Harvey P. Dale, Nov 17 2018 *)

Crossrefs

A000217 Triangular numbers. A001969 Evil numbers.

Sequence in context: A105594 A091949 A039984 * A319102 A103582 A129565

Adjacent sequences: A153636 A153637 A153638 * A153640 A153641 A153642

Keyword

nonn

Author

Tanya Khovanova, Dec 29 2008

Status

approved