A110853 Squares of the form prime(k)*(k+1)^2 + 1.

9, 81, 1089

Offset

1,1

Comments

No further terms less than 4.89*10^24 (n=62662502). - Ray Chandler, Sep 26 2005

Links

Table of n, a(n) for n=1..3.

Example

prime(1)*(1+1)^2+1 = 2*4+1 = 9 = 3^2.
prime(3)*(3+1)^2+1 = 5*42+1 = 81 = 9^2.
prime(7)*(7+1)^2+1 = 31*100+1 = 1089 = 33^2.

Mathematica

Do[ s = Prime[n](n + 1)^2 + 1; If[ IntegerQ[ Sqrt[s]], Print[s]], {n, 5000000}] (* Robert G. Wilson v, Sep 26 2005 *)

Crossrefs

Sequence in context: A069659 A271556 A368446 * A371640 A344402 A167723

Adjacent sequences: A110850 A110851 A110852 * A110854 A110855 A110856

Keyword

nonn,bref,more,hard

Author

Giovanni Teofilatto, Sep 17 2005

Extensions

Edited by Ray Chandler, Sep 26 2005

Status

approved