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A229157 Primes of the form T(n) + C(n) - 1 where T(n) and C(n) are n-th triangular and cube numbers. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified January 22 02:46 EST 2022. Contains 350481 sequences. (Running on oeis4.)