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A331079
a(n) = Sum_{i=1..n} u_2(i)*u_2(i+1), where u_2(n) = A038548(n).
1
1, 2, 4, 6, 8, 10, 12, 16, 20, 22, 25, 28, 30, 34, 40, 43, 46, 49, 52, 58, 62, 64, 68, 76, 80, 84, 90, 93, 97, 101, 104, 110, 114, 118, 128, 133, 135, 139, 147, 151, 155, 159, 162, 171, 177, 179, 184, 194, 200, 206, 212, 215, 219, 227, 235, 243, 247, 249, 255, 261
OFFSET
1,2
COMMENTS
For background references see A330570.
LINKS
MATHEMATICA
With[{s = Table[Ceiling[DivisorSigma[0, n] / 2], {n, 1, 100}]}, Accumulate[Most[s] * Rest[s]]] (* Amiram Eldar, Apr 19 2024 *)
CROSSREFS
Sequence in context: A015926 A085154 A371286 * A274284 A375473 A112421
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 10 2020
STATUS
approved