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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.
0
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
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
KEYWORD
nonn
AUTHOR
Jake Foster, Sep 29 2011
STATUS
approved