A139328 Sums of rows of the triangle in A139325.

0, 3, 6, 10, 14, 19, 24, 30, 36, 45, 52, 60, 67, 76, 86, 96, 105, 117, 127, 138, 151, 162, 176, 189, 203, 216, 230, 246, 262, 277, 292, 308, 325, 343, 362, 376, 398, 417, 435, 451, 473, 491, 515, 535, 557, 579, 599, 622, 646, 668, 691, 712, 737, 764, 788, 815

Offset

1,2

Comments

a(n) = Sum(A139325(n,k): 1<=k<=n).

Links

Table of n, a(n) for n=1..56.

Formula

a(n) = A000720(2*n^2 - 1) - 1.

Example

a(4)=#{3,5,7}+#{11,13}+#{17,19,23}+#{29,31}}=3+2+3+2}=10:
..1 ...3 ...5 ...7 ... primes in first row = {3,5,7},
..9 ..11 ..13 ..15 ... primes in 2nd row = {11,13},
.17 ..19 ..21 ..23 ... primes in 3rd row = {17,19},
.25 ..27 ..29 ..31 ... primes in 4th row = {29,31}.

Crossrefs

Cf. A038107.

Sequence in context: A310069 A310070 A036572 * A253620 A282731 A134919

Adjacent sequences: A139325 A139326 A139327 * A139329 A139330 A139331

Keyword

nonn

Author

Reinhard Zumkeller, Apr 14 2008

Status

approved