A137446 Positive numbers k such that k^2 +- (k-1) are primes.

2, 3, 4, 6, 9, 13, 15, 16, 21, 28, 39, 55, 60, 70, 76, 100, 120, 144, 148, 154, 163, 169, 174, 193, 195, 219, 246, 288, 294, 330, 343, 349, 358, 393, 396, 405, 448, 456, 490, 496, 501, 519, 541, 561, 573, 604, 606, 610, 625, 763, 769, 786, 856, 921, 994, 1023

Offset

1,1

Links

T. D. Noe, Table of n, a(n) for n=1..1000

Example

2^2 +- 1 -> (3,4) Primes,
3^2 +- 2 -> (7,11) Primes,
13^2 +- 12 -> (157,181) Prime,...

Mathematica

Select[Range[500], PrimeQ[ #^2-(#-1)]&&PrimeQ[ #^2+(#-1)]&]

Crossrefs

Sequence in context: A057287 A056751 A189035 * A240028 A097557 A175848

Adjacent sequences: A137443 A137444 A137445 * A137447 A137448 A137449

Keyword

nonn,changed

Author

Vladimir Joseph Stephan Orlovsky, Apr 21 2008

Extensions

Extended by T. D. Noe, Dec 14 2008

Status

approved