A007944 a(n) is the largest even number k such that 6, 8, ..., k are sums of 2 of first n odd primes.

6, 10, 14, 18, 26, 30, 38, 42, 42, 54, 62, 74, 74, 90, 90, 90, 108, 114, 114, 134, 134, 146, 162, 172, 180, 186, 186, 218, 222, 230, 240, 240, 254, 258, 270, 270, 290, 290, 290, 330, 348, 348, 366, 366, 366, 398, 398, 410, 410, 434, 440, 440, 474, 474, 474, 474, 474, 522

Offset

1,1

Links

David A. Corneth, 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!

Formula

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

More specifically, a(n) <= 2*prime(n+1). On the Goldbach conjecture a(n) >= prime(n+1) + 3. - Charles R Greathouse IV, Dec 09 2014

Mathematica

Table[tot = Total /@ Tuples[Prime[Range[2, n + 1]], 2]; lim = Last@tot; First[Select[Range[6, lim, 2], ! MemberQ[tot, #] &] - 2, lim], {n, 58}] (* Robert Price, Apr 26 2025 *)

Prog

(PARI) first(n) = {n+=3; my(fnf = 6, pr = primes(n), found = vector(pr[n]), res = vector(n-3), start = 2); for(i = 2, n-2, for(j = start, i, found[(pr[i]+pr[j])>>1] = 1); for(j = fnf>>1, pr[n], if(found[j]==0, fnf = j<<1; break)); while(pr[start] + pr[i+1]<fnf, start++); while(pr[start]+pr[i+1]>fnf, start--); res[i-1]=fnf-2); res} \\ David A. Corneth, Jul 06 2017

Crossrefs

Sequence in context: A315189 A315190 A315191 * A290266 A200269 A357894

Adjacent sequences: A007941 A007942 A007943 * A007945 A007946 A007947

Keyword

nonn,easy

Author

R. Muller

Extensions

More terms from David W. Wilson

Status

approved