A071644 - OEIS

%I #9 Jan 31 2022 19:37:49

%S 1,311,433380445,10478887384420274295559,

%T 72383623935281195994580596438773770789899563140885,

%U 39891231890836797259743675264050089835308134898303203181868683359843686746718703346865629969758112672725599

%N a(n) = A005148(2^n-1)/8^(n-1).

%C Appears to always be an integer. General conjecture: the numbers k such that 8^a is the highest power of 2 dividing A005148(k) is the same sequence as numbers k such that k has exactly (a+1) 1's in its binary representation. Hence this sequence gives the smallest integer of the form A005148(k) /8^(n-1).

%o (PARI) for(s=1,8,n=2^s-1; print1(polcoeff(prod(k=1,(n+1)\2,1+x^(2*k-1),1+x*O(x^n))^(24*n),n)/24/8^(s-1),","))

%K easy,nonn

%O 1,2

%A _Benoit Cloitre_, Jun 22 2002