A211873 Numbers b >= 0 such that 2 b^2 + 3 b + 5 is prime.

0, 2, 8, 14, 22, 24, 28, 42, 52, 58, 62, 64, 72, 84, 92, 94, 98, 114, 122, 134, 142, 148, 168, 178, 188, 202, 212, 218, 244, 248, 262, 274, 282, 302, 304, 308, 314, 318, 324, 328, 338, 342, 352, 358, 364, 372, 374, 392, 394, 398, 402, 408, 414, 434, 442, 448, 478, 484, 492, 498

Offset

1,2

Comments

An example of Sun's conjecture in A217788: For a(n)>5, also bases b such [2;3;5] seen as a number written in base b, is prime.

Links

Paolo P. Lava, Table of n, a(n) for n = 1..1000

Prog

(PARI) n=#v=[2, 3, 5]; for(b=0, 500, ispseudoprime(sum(k=1, n, b^(n-k)*v[k]))&print1(b", "))
(Magma) [b: b in [0..500] | IsPrime(2*b^2+3*b+5)]; // Bruno Berselli, Apr 11 2013

Crossrefs

Cf. A224217.

Sequence in context: A064148 A246299 A161464 * A248057 A121055 A344161

Adjacent sequences: A211870 A211871 A211872 * A211874 A211875 A211876

Keyword

nonn

Author

M. F. Hasler, Mar 31 2013

Status

approved