A110979 Squares equal to the sum of the first k primes minus 1.

1, 4, 9, 16, 196, 839056, 7796654478001

Offset: 1

Author

Giovanni Teofilatto, Sep 30 2005

Keywords

• nonn
• hard
• more

Comments

No more terms < 7472966967498, sum of first 10^6 primes minus 1. - Ray Chandler, Oct 07 2005

Crossrefs

Cf. A007504, A110997.

Intersection of A000290 and A237589.

Programs

Mathematica

Select[Accumulate[Prime[Range[1000]]]-1,IntegerQ[Sqrt[#]]&] (* Harvey P. Dale, Jun 09 2022 *)

PARI

lista(nn) = my(s=-1); forprime(p=2, nn, s+=p; if(issquare(s), print1(s, ", "))) \\ Jinyuan Wang, Aug 10 2023

Extensions

a(6) corrected by Ray Chandler, Oct 07 2005

a(7) from Jinyuan Wang, Aug 10 2023