A112559 Numbers k such that both k and 4k + 1 are in A005098.

3, 9, 18, 24, 48, 69, 93, 102, 108, 144, 168, 177, 213, 249, 258, 273, 282, 324, 357, 363, 387, 399, 438, 444, 504, 507, 573, 609, 669, 678, 738, 759, 762, 777, 807, 864, 867, 909, 942, 948, 963, 1014, 1068, 1074, 1182, 1197, 1248, 1299, 1389, 1392, 1413, 1488

Offset

1,1

Comments

All terms are multiples of 3.

Numbers k such that 4*k+1 and 16*k+5 are both prime. - Vincenzo Librandi, Dec 13 2010

These k cannot have least significant digits 0, 1, 5, or 6. - J. M. Bergot, Jul 06 2011

Links

R. J. Mathar, Table of n, a(n) for n = 1..1738

Formula

a(n) = 3 * A179652(n). - Joerg Arndt, Jul 10 2011

Prog

(Magma) [n: n in [0..3000] | IsPrime(4*n+1)and IsPrime(16*n+5)] // Vincenzo Librandi, Dec 13 2010

Crossrefs

Cf. A002144, A175600.

Sequence in context: A360365 A310332 A210991 * A030784 A203594 A325751

Adjacent sequences: A112556 A112557 A112558 * A112560 A112561 A112562

Keyword

nonn

Author

Zak Seidov, May 26 2007

Status

approved