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A178689 Partial sums of A122836 (number of topologies on n labeled elements in which at least one element belongs to some pair of noncomparable members of the topology). 0
0, 0, 0, 10, 253, 6384, 208887, 9673189, 651633791, 63901292323, 9040801794022, 1825884406581355, 521181413335003984, 20788660474279716434454, 136405712435371969786250, 88872674830676191675804592 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

All listed (the first 16) values are nonprimes. In the underlying sequence, only A122836(5) = 6131 is prime of the listed values.

LINKS

Table of n, a(n) for n=0..15.

FORMULA

a(n) = SUM[i=0..n] A122836(i) = SUM[i=0..n] (A000798(i) - A122835(i)) = (SUM[i=0..n] A000798(i)) - (SUM[i=0..n] A122835(i)).

EXAMPLE

a(4) = 0 + 0 + 0 + 10 + 243 = 253 = 11 * 23.

CROSSREFS

Cf. A000798, A122835, A122836.

Sequence in context: A240289 A001536 A114450 * A095983 A059166 A100743

Adjacent sequences:  A178686 A178687 A178688 * A178690 A178691 A178692

KEYWORD

nonn

AUTHOR

Jonathan Vos Post, Dec 25 2010

STATUS

approved

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Last modified May 24 20:53 EDT 2019. Contains 323534 sequences. (Running on oeis4.)