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A173488 Partial sums of A055512. 0
1, 2, 4, 10, 46, 426, 6816, 164778, 5561666, 248740730, 14187451940, 1002045820690, 85615117761142, 8682866612715706, 1029036311254555560, 140656568448867136650, 21929110364021381812410, 3862525357012048643891882, 762298016068721625860646524 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Partial sums of the number of lattices with n labeled elements. After a(0) = 1, always even, hence the only prime in the partial sum is 2. The subsequence of semiprimes begins 4, 10, 46.

LINKS

Table of n, a(n) for n=0..18.

FORMULA

a(n) = Sum_{i=0..n} A055512(i).

MATHEMATICA

Cases[Import["https://oeis.org/A055512/b055512.txt", "Table"], {_, _}][[All, 2]] // Accumulate (* Jean-François Alcover, Jan 02 2020 *)

CROSSREFS

Cf. A055512, A006966, A001035, Main diagonal of A058159.

Sequence in context: A344790 A028404 A113208 * A000613 A322294 A053500

Adjacent sequences:  A173485 A173486 A173487 * A173489 A173490 A173491

KEYWORD

nonn,hard,more

AUTHOR

Jonathan Vos Post, Feb 19 2010

EXTENSIONS

a(17)-a(18) from Jean-François Alcover, Jan 02 2020

STATUS

approved

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Last modified June 14 19:28 EDT 2021. Contains 345038 sequences. (Running on oeis4.)