A214519 Least number m such that 4*m^2 + 1 is prime and the next prime of this form is 4*(m + A214518(n))^2 + 1.

1, 3, 13, 20, 47, 92, 175, 248, 1695, 1768, 22685, 41367, 49532, 178582, 420452, 1940278, 13957468, 20258760

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Mathematica

n = 1; last = 1; t = {1}; t2 = {1}; While[Length[t] < 10, n++; p = 1 + 4 n^2; If[PrimeQ[p], If[n - last > t[[-1]], AppendTo[t, n - last]; AppendTo[t2, last]]; last = n]]; t2

Crossrefs

Cf. A121326 (primes of the form 1+4*n^2), A214517, A214518 (record differences).

Sequence in context: A178712 A273686 A215567 * A099502 A145024 A055059

Adjacent sequences: A214516 A214517 A214518 * A214520 A214521 A214522

Keyword

nonn,hard,more

Author

T. D. Noe, Aug 06 2012

Status

approved