A007962 a(n) is the largest odd number k such that 9, 11, ..., k are sums of 3 of first n odd primes.

9, 15, 21, 29, 39, 47, 57, 65, 71, 93, 99, 115, 129, 137, 143, 149, 183, 189, 205, 219, 225, 241, 251, 269, 287, 309, 317, 327, 335, 357, 371, 377, 417, 419, 441, 459, 465, 493, 503, 509, 543, 545, 567, 587, 597, 609, 621, 653, 657, 695, 701, 723, 725, 743, 749, 755, 785

Offset: 1

Author

R. Muller

Keywords

• nonn

Comments

From Rémy Sigrist, Aug 20 2017: (Start)

The following table gives the first index (n0) of the term that starts the first run of j consecutive equal terms for j=1..6:

j n0 a(n0)

- ---- ------

1 1 9

2 96 1511

3 131 2205

4 334 6733

5 5959 176843

6 3079 84731

(End)

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• K. Kashihara, Comments and Topics on Smarandache Notions and Problems, Erhus University Press, 1996, 50 pages. See page 20.
• K. Kashihara, Comments and Topics on Smarandache Notions and Problems, Erhus University Press, 1996, 50 pages. [Cached copy] See page 20.
• F. Smarandache, Only Problems, Not Solutions!
• Rémy Sigrist, PARI program for A007962

Programs

Mathematica

nmax = 100; p = pq = pqr = {}; u = 9;
Reap[For[n = 1, n <= nmax, n++, o = Prime[n+1]; p = Union[p, {o}]; pq = Union[pq, p+o]; pqr = Union[pqr, pq+o]; While[MemberQ[pqr, u], u += 2]; Sow[u-2]]][[2, 1]] (* Jean-François Alcover, Dec 19 2017, after Rémy Sigrist *)

PARI

See Links section.

Formula

a(n) << n log n. - Charles R Greathouse IV, Sep 19 2012