A103777 Numbers n such that f[n],f[n+1]and f[n+2] are all primes, where f[n]=8*n^2+4*n+1.

15, 50, 80, 110, 230, 245, 425, 570, 635, 645, 710, 925, 1440, 1645, 1710, 1815, 2000, 2465, 2635, 2940, 3040, 3090, 3195, 3525, 4260, 4310, 4400, 4885, 5960, 6145, 7030, 7120, 7250, 8430, 8890, 9445, 10265, 11060, 11150, 11710, 11775, 13020, 13565

Offset

1,1

Comments

All terms are divisible by 5, hence conjecture: there is no such n that f[n],f[n+1],f[n+2] and f[n+3] are primes.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

15 is a term because f[15]=1861, f[16]=2113 and f[17]=2381 are all primes.

Mathematica

 Flatten[Position[Partition[Table[PrimeQ[8n^2+4n+1], {n, 14000}], 3, 1], {True, True, True}]] (* Harvey P. Dale, Oct 08 2012 *)

Crossrefs

Cf. A102083, A103776.

Sequence in context: A020257 A298511 A349855 * A134742 A318084 A191746

Adjacent sequences: A103774 A103775 A103776 * A103778 A103779 A103780

Keyword

nonn

Author

Zak Seidov, Feb 15 2005

Status

approved