A229157 Primes of the form T(n) + C(n) - 1 where T(n) and C(n) are n-th triangular and cube numbers.

73, 139, 547, 773, 2287, 4231, 8209, 9491, 36497, 111767, 118873, 177211, 217829, 316777, 391717, 596273, 889391, 1005049, 1035451, 1163189, 1265597, 1301023, 1449337, 1735259, 2105407, 2524771, 3319123, 4755827, 5467351, 6246523, 6348829, 6662437, 8636239, 9151273

Offset

1,1

Comments

Also primes of the form (2*n^3 + n^2 + n - 2)/2.

Links

K. D. Bajpai, Table of n, a(n) for n = 1..5000

Example

a(3)=547: T(8)+C(8)-1 = (1/2)*8*(8+1)+8^3-1 = 547 which is prime.
a(4)=773: T(9)+C(9)-1 = (1/2)*9*(9+1)+9^3-1 = 773 which is prime.

Maple

KD:= proc() local a, b, d; a:= (1/2)*n*(n+1); b:=n^3; d:=a+b-1; if isprime(d) then   RETURN(d): fi; end:seq(KD(), n=1..500);

Crossrefs

Cf. A120479, A229080.

Sequence in context: A064668 A196655 A196656 * A037994 A138642 A142179

Adjacent sequences: A229154 A229155 A229156 * A229158 A229159 A229160

Keyword

nonn

Author

K. D. Bajpai, Sep 15 2013

Status

approved