1,3

Each term in the sequence (n>1) = sum of previous terms of triangle A137680 = partial sums of sequence A137681: (1, 2, 4, 10, 23,...).

Partial sums of sequence A137681 prefaced with a 1. a(n) = sum of all terms in rows 1 through (n-1) in triangle A137680.

First few rows of triangle A137680 =

1;

1, 1;

3, 0, 1;

7, 2, 0, 1;

...

a(5) = 17 = sum of 1 through 4 row terms of triangle A137680: (1 + 2 + 4 + 10); where (1, 2, 4, 10, 23,...) = A137681 = row sums of triangle A137680 = first difference row of A137682, n>1.

Cf. A137680, A137681.

Sequence in context: A147142 A106472 A036885 this_sequence A000600 A131056 A077851

Adjacent sequences: A137679 A137680 A137681 this_sequence A137683 A137684 A137685

nonn

Gary W. Adamson (qntmpkt(AT)yahoo.com), Feb 05 2008