A078706 a(n) = smallest integer >=a(n-1) such that sum of first n terms is prime.

2, 3, 6, 6, 6, 6, 8, 10, 12, 12, 12, 14, 16, 18, 18, 18, 24, 32, 34, 36, 38, 42, 46, 48, 54, 56, 64, 68, 78, 90, 90, 94, 102, 114, 122, 124, 134, 144, 148, 150, 152, 160, 168, 170, 178, 182, 190, 192, 200, 216, 220, 222, 234, 234, 234, 246, 260, 264, 268, 270, 278, 280

Offset

1,1

Links

Ivan Neretin, Table of n, a(n) for n = 1..10000

Example

a(1)=2, the first prime. The smallest integer >=2 that yields a prime when added to 2 is 3, so a(2)=3. The smallest integer >=3 that yields a prime when added to 2+3 is 6 so a(3)=6.

Mathematica

s = 0; NestList[(s += #; NextPrime[s + # - 1] - s) &, 2, 61] (* Ivan Neretin, May 14 2015 *)

Crossrefs

Cf. A051935.

Sequence in context: A290223 A274213 A350315 * A077082 A333936 A193896

Adjacent sequences: A078703 A078704 A078705 * A078707 A078708 A078709

Keyword

easy,nonn

Author

Neil Fernandez, Dec 18 2002

Status

approved