A071196 The sum of the sequence starting with prime(n) and having prime sum defined in A071194, or -1 if no such sequence exists.
5, 127, 23, 31, 41, 101, 59, 71, 83, 97, 109, 479, 131, 263, 431, 173, 331, 199, 211, 223, 421, 251, 269, 719, 757, 311, 827, 587, 349, 647, 683, 1367, 733, 439, 457, 811, 487, 503, 2141, 1747, 941, 5009, 991, 1951, 607, 2053, 661, 1151, 21139, 701, 1753
Offset: 1
Examples
n=25: prime(25)=97, sum=97+101+103+107+109+113+127=757=a(25), prime; shorter (length>1) partial sums are composite: {97,198,301,408,517,630,757}.
Links
- Rémy Sigrist, Table of n, a(n) for n = 1..10000
- Rémy Sigrist, Colored logarithmic scatterplot of the first 10000 terms (where the color is function of A071194(n))
Programs
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Mathematica
Table[sm = Prime[k] + Prime[k + 1]; g = 1; While[ ! PrimeQ[sm], g++; sm = sm + Prime[k + g]]; sm, {k, 1, 51}] (* Lei Zhou, Dec 02 2005 *) -
PARI
{ forprime (p=2, prime(51), s=p; forprime (q=p+1, oo, if (isprime(s+=q), print1 (s", "); break))) } \\ Rémy Sigrist, Nov 17 2020
Extensions
Edited and escape clause added by N. J. A. Sloane, Nov 17 2020~