A086678 Numbers n such that 1 + Sum_{k=1..n} 2k^5 is a prime.

1, 2, 8, 9, 11, 20, 27, 36, 41, 42, 71, 77, 86, 95, 105, 110, 113, 132, 134, 137, 138, 147, 149, 155, 183, 186, 189, 201, 209, 210, 212, 215, 218, 222, 230, 245, 258, 261, 278, 309, 317, 329, 336, 341, 347, 359, 371, 377, 380, 389, 411, 413, 417, 425, 432, 435

Offset

1,2

Links

Table of n, a(n) for n=1..56.

Formula

(2*n^6+6*n^5+5*n^4-n^2+6)/6 is prime.

Example

Sum(k=1,2,2k^5)+1 = 2*1^5+2*2^5 + 1 = 67 is a prime so 2 belongs to the sequence.

Crossrefs

A091872 gives corresponding primes.

Sequence in context: A030334 A338807 A020676 * A359771 A289146 A294374

Adjacent sequences: A086675 A086676 A086677 * A086679 A086680 A086681

Keyword

nonn,easy

Author

Yalcin Aktar, Jul 28 2003

Extensions

More terms from Ray Chandler, Aug 07 2003

Status

approved