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A134180 Indices of k prime sums in A134179. +0
2
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 (list; graph; listen)
OFFSET

1,2

FORMULA

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

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.

PROGRAM

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. A134179 A134244 A134245 A134246.

Adjacent sequences: A134177 A134178 A134179 this_sequence A134181 A134182 A134183

Sequence in context: A089228 A126278 A133847 this_sequence A107220 A098758 A029608

KEYWORD

easy,nonn,uned

AUTHOR

Enoch Haga (Enokh(AT)comcast.net), Oct 16 2007

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Last modified October 11 13:47 EDT 2008. Contains 144830 sequences.


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