A091860 a(1)=1, a(n)=sum(i=1,n-1,b(i)) where b(i)=0 if a(i) and a(n-i) are both even, b(i)=1 otherwise.

1, 1, 2, 3, 4, 4, 6, 5, 6, 6, 8, 6, 8, 8, 8, 7, 8, 8, 10, 8, 10, 10, 10, 8, 10, 10, 10, 10, 10, 10, 10, 9, 10, 10, 12, 10, 12, 12, 12, 10, 12, 12, 12, 12, 12, 12, 12, 10, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 11, 12, 12, 14, 12, 14, 14, 14, 12, 14, 14, 14, 14, 14

Offset

1,3

Links

Table of n, a(n) for n=1..77.

Formula

n>1 a(2n)=a(n)+2; if n is a power of 2, a(2n+1)=1+a(2n); if n is the sum of 2 distinct power of 2, a(2n+1)=2+a(2n); a(2n+1)=a(2n) otherwise

Prog

(PARI) an[1]=1; for(n=2, 100, an[n]=sum(i=1, n-1, max(a(i)%2, a(n-i)%2)))

Crossrefs

Cf. A018900, A072823.

Sequence in context: A008328 A298933 A365851 * A333995 A301764 A181833

Adjacent sequences: A091857 A091858 A091859 * A091861 A091862 A091863

Keyword

nonn

Author

Benoit Cloitre, Mar 16 2004

Status

approved