A101693 - OEIS

%I #5 Nov 23 2019 12:55:19

%S 1,1,5,1,21,1,5,17,341,1,5,17,85,257,1285,4369,87381,1,5,17,85,257,

%T 1285,4369,21845,65537,327685,1114129,5570645,16843009,84215045,

%U 286331153,5726623061,1,5,17,85,257,1285,4369,21845,65537,327685,1114129,5570645

%N A modular binomial sum transform of 2^n.

%C a(2^n)=A101694(n); b(2^n+1) is 5,1,1,1,....

%F a(n)=sum{k=0..n, mod(binomial(2n-2, k), 2)2^k}

%t Table[Sum[Mod[Binomial[2n-2,k],2]2^k,{k,0,n}],{n,0,50}] (* _Harvey P. Dale_, Nov 23 2019 *)

%Y Cf. A001045.

%K easy,nonn

%O 0,3

%A _Paul Barry_, Dec 11 2004