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 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. 0

%I

%S 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,

%T 10,10,9,10,10,12,10,12,12,12,10,12,12,12,12,12,12,12,10,12,12,12,12,

%U 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

%N 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.

%F 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

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

%Y Cf. A018900, A072823.

%K nonn

%O 1,3

%A _Benoit Cloitre_, Mar 16 2004

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Last modified January 15 12:14 EST 2021. Contains 340187 sequences. (Running on oeis4.)