A196223 Natural numbers n such that Sum_{k = 1..pi(n)-1} p(k) == p(pi(n)) mod n, where p(k) denotes the k-th prime and pi(n) is the number of primes strictly less than n.

6, 7, 15, 27, 41, 55, 172, 561, 1334, 6571, 11490, 429705, 2173016, 4417701, 9063353, 9531624, 40411847, 64538709, 83537963, 121316228, 181504240, 222586609

Offset

1,1

Links

Table of n, a(n) for n=1..22.

G. L. Honaker, Jr. and Chris Caldwell, Prime Curios! 6571

Example

2+3+5+7+11==13 (mod 15) and so 15 has this property.

Mathematica

Reap[Module[{c = 0}, For[n = 4, n <= 10^6, n++, If[PrimeQ[n - 1], c += NextPrime[n - 1, -1]]; If[Mod[c, n] == NextPrime[n, -1], Sow[n]]]]]

Crossrefs

Cf. A000720.

Sequence in context: A165767 A292348 A319185 * A106680 A214325 A078388

Adjacent sequences: A196220 A196221 A196222 * A196224 A196225 A196226

Keyword

nonn

Author

Jake Foster, Sep 29 2011

Status

approved