A254616 Let i < k and prime(k) == x(i) mod prime(i). This sequence gives the indices k of the primes prime(k) such that Sum(i=1..k-1, x(i)) is prime.

3, 6, 9, 30, 33, 36, 38, 54, 66, 89, 92, 93, 98, 121, 125, 128, 154, 155, 167, 189, 198, 231, 291, 296, 300, 310, 323, 334, 345, 357, 373, 407, 436, 437, 444, 456, 481, 483, 492, 493, 515, 516, 541, 554, 581, 628, 649, 681, 713, 714, 749, 750, 809, 818, 826, 834, 864, 868, 872, 881, 888

Offset

1,1

Links

Table of n, a(n) for n=1..61.

Example

prime(3) is 5, 5 == 1 mod 2 == 2 mod 3. 1 + 2 = 3, which is prime. Therefore, the index of the prime(3) is in the sequence.

Mathematica

lst1={}; lst2={}; i=1; primes=Prime[Range[1000]];
Do[
   While[i<k, AppendTo[lst1, Mod[primes[[k]], primes[[i]]]]; i++];
   If[PrimeQ[Total[lst1]], AppendTo[lst2, k]];
   i=1; lst1={},
   {k, 3, Length[primes]}
];
lst2

Crossrefs

Cf. A000040.

Sequence in context: A349597 A178467 A193802 * A195205 A045638 A305322

Adjacent sequences: A254613 A254614 A254615 * A254617 A254618 A254619

Keyword

easy,nonn

Author

Ivan N. Ianakiev, Feb 03 2015

Status

approved