A134180 Indices of primes in A007468.

1, 3, 5, 7, 9, 13, 23, 25, 29, 55, 117, 119, 123, 173, 187, 193, 205, 213, 223, 249, 255, 259, 265, 285, 299, 311, 329, 351, 393, 397, 411, 483, 487, 513, 515, 525, 563, 587, 597, 607, 637, 645, 647, 679, 709, 789, 871, 877, 911, 953, 971, 985, 1015, 1051, 1075

Offset

1,2

Comments

Compute sums of k distinct sequential primes (no overlap). If the sums are prime add their indices to the sequence.

Links

Chai Wah Wu, Table of n, a(n) for n = 1..1000

Example

a(2)=3 because this k value is the index for the next 3 primes in sequence to be summed. k=1 is 2, k=2 is 3+5 and k=3 is 7+11+13=31. The sums at k=1 and k=3 are prime, while k=2 is composite.

Prog

(UBASIC)
  10 K=1
  20 A=nxtprm(A): B=B+A: C=C+1: if C<>K then 20: else 30
  30 L=B/K
  31 print K; B; : Q=prmdiv(B): if Q=B then print B; "-": stop: else 40
  40 B=0: K=K+1: C=0: goto 20

Crossrefs

Cf. A007468. Corresponding primes are listed in A134179.

Cf. A134244, A134245, A134246.

Sequence in context: A089228 A262602 A133847 * A107220 A249412 A098758

Adjacent sequences: A134177 A134178 A134179 * A134181 A134182 A134183

Keyword

easy,nonn

Author

Enoch Haga, Oct 16 2007

Status

approved