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

Author

K. D. Bajpai, Sep 15 2013

Keywords

• nonn

Comments

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

Examples

			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.
		

Links

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

Crossrefs

Cf. A120479, A229080.

Programs

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);