A058871 Sum of next n primes (A007468) is prime for odd n or half the sum is prime for even n.

1, 3, 5, 7, 9, 13, 18, 20, 23, 25, 29, 48, 55, 98, 117, 119, 123, 130, 173, 187, 193, 198, 205, 213, 218, 223, 248, 249, 255, 259, 265, 268, 285, 292, 299, 311, 329, 346, 351, 386, 390, 393, 397, 411, 412, 448, 483, 487, 513, 515, 525, 554, 563, 574, 587, 597

Offset

1,2

Links

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

Mathematica

Do[ s = Sum[ Prime[i], {i, n(n-1)/2 + 1, n(n+1)/2} ]; If[ PrimeQ[s] || PrimeQ[s/2], Print[n] ], {n, 10^3} ]

Crossrefs

Cf. A007468.

Sequence in context: A182058 A200975 A370452 * A126278 A121259 A211139

Adjacent sequences: A058868 A058869 A058870 * A058872 A058873 A058874

Keyword

nonn

Author

Robert G. Wilson v, Jan 06 2001

Status

approved