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

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, 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, 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

Offset

0,6

Comments

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

Links

Table of n, a(n) for n=0..111.

Mathematica

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

Crossrefs

Cf. A173631, A002110, A000040.

Sequence in context: A107081 A029526 A219949 * A061060 A084307 A066918

Adjacent sequences: A173629 A173630 A173631 * A173633 A173634 A173635

Keyword

nonn,changed

Author

Vladimir Shevelev, Nov 23 2010

Extensions

Extended by T. D. Noe, Nov 23 2010

Status

approved