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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 (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 FORMULA a(n) = SUM[i=0..n] A055512(i). EXAMPLE a(18) = 1 + 1 + 2 + 6 + 36 + 380 + 6390 + 157962 + 5396888 + 243179064 + 13938711210 + 987858368750 + 84613071940452 + 8597251494954564 + 1020353444641839854 + 139627532137612581090 + 21788453795572514675760 + 3840596246648027262079472 + 758435490711709577216754642. CROSSREFS Cf. A055512, A006966, A001035, Main diagonal of A058159. Sequence in context: A125805 A028404 A113208 * A000613 A053500 A214724 Adjacent sequences:  A173485 A173486 A173487 * A173489 A173490 A173491 KEYWORD hard,nonn AUTHOR Jonathan Vos Post, Feb 19 2010 STATUS approved

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Last modified May 22 09:43 EDT 2013. Contains 225519 sequences.