A139321 First occurrence of n in A068307: least number k such that the number of decomposition of k into the sum of three primes is n.

1, 6, 9, 15, 17, 21, 31, 27, 35, 33, 39, 41, 45, 47, 55, 51, 53, 57, 242, 63, 67, 65, 71, 476, 79, 81, 578, 85, 77, 83, 99, 572, 512, 89, 97, 95, 103, 111, 101, 692, 1040, 632, 115, 107, 782, 129, 121, 113, 902, 141, 119, 842, 992, 125, 133, 147, 1520, 131, 159, 145

Offset: 0

Author

Robert G. Wilson v, Apr 13 2008

Keywords

• nonn

Comments

Records (differs from A139322): 1, 6, 9, 15, 17, 21, 31, 35, 39, 41, 45, 47, 55, 57, 242, 476, 578, 692, 1040, 1520, 1898, 2162, 2480, 3536, 4004, 4034, 4526, 5456, 5918, 7010, 8804, 9740, 10106, 10262, 10412, 10622, 10772, 10952, 11462, 12362, 12452, 12512, 12560, 12662, 12902, ... .

Links

• Robert G. Wilson v and T. D. Noe, Table of n, a(n) for n = 0..2500

Crossrefs

Cf. A000040, A068307. Records: A139322.

Programs

Mathematica

f[n_] := Block[{c = 0, lmt = PrimePi@ Floor[n/2], p, q}, Do[p = Prime@ i; q = Prime@ j; r = n - p - q; If[ PrimeQ@ r && r >= p, c++ ], {i, lmt}, {j, i}]; c]; t = Table[0, {1000}]; Do[a = f@n; If[t[[a]] == 0, t[[a]] = n; Print[{a, n}]], {n, 10^6}]