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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 12 14:35 EST 2019. Contains 329058 sequences. (Running on oeis4.)