A173632 - OEIS

A173632

a(n)=sqrt((A173631(n))^2-4*P_n), where P_n is product of first n primes, if this value is integral and a(n)=0, otherwise.

%I #18 Apr 06 2026 22:47:08

%S 0,1,1,1,1,13,17,1,41,157,0,0,0,0,17659,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

%U 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0

%N a(n)=sqrt((A173631(n))^2-4*P_n), where P_n is product of first n primes, if this value is integral and a(n)=0, otherwise.

%C a(14) appears to be the last nonzero term.

%t p=4; Join[{0}, Table[p=p*Prime[n]; q=Sqrt[Ceiling[Sqrt[p]]^2-p]; If[IntegerQ[q], q, 0], {n, 200}]]

%Y Cf. A173631, A002110, A061060.

%K nonn

%O 0,6

%A _Vladimir Shevelev_, Nov 23 2010

%E Extended by _T. D. Noe_, Nov 23 2010