A261366 a(n) = number of even terms in row n of triangle A261363.

0, 1, 1, 2, 1, 4, 3, 4, 1, 8, 7, 8, 5, 10, 7, 8, 1, 16, 15, 16, 13, 18, 15, 16, 9, 22, 19, 20, 13, 22, 15, 16, 1, 32, 31, 32, 29, 34, 31, 32, 25, 38, 35, 36, 29, 38, 31, 32, 17, 46, 43, 44, 37, 46, 39, 40, 25, 50, 43, 44, 29, 46, 31, 32, 1, 64, 63, 64, 61

Offset: 0

Author

Reinhard Zumkeller, Aug 16 2015

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A261363, A001316.

Programs

Haskell

a261366 = sum . map ((1 -) . flip mod 2) . a261363_row

Mathematica

a[n_] := Count[Accumulate[Array[Boole[0 == BitAnd[n - #, #]] &, n + 1, 0]], ?EvenQ]; Array[a, 100, 0] (* _Amiram Eldar, May 13 2025 *)

Formula

For n > 0: a(n) = n + 1 - A001316(n-1).