

A070880


Look at all 2^(n1)1 nonempty subsets S of {1, 2, ..., n1}; a(n) gives number of such S with property that it is impossible to partition n into parts from S such that each s in S is used at least once.


3



0, 0, 1, 3, 10, 22, 52, 110, 234, 482, 987, 1997, 4035, 8113, 16288, 32644, 65388, 130886, 261922, 524013, 1048250, 2096752, 4193831, 8388033, 16776543, 33553621, 67107918, 134216596, 268434139, 536869354, 1073740011, 2147481510, 4294964833, 8589931699
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OFFSET

1,4


LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..100


FORMULA

a(n) = 2^(n1)  A088314(n).  Charlie Neder, Feb 08 2019


EXAMPLE

a(4)=3 because there are three different subsets S of {1,2,3} satisfying the condition: {3}, {2,3} & {1,2,3}. For the other subsets S, such as {1,2}, there is a partition of 4 which uses them all (such as 4 = 1+1+2).


CROSSREFS

Cf. A088314, A088528.
Sequence in context: A294414 A299336 A222629 * A321335 A171686 A027164
Adjacent sequences: A070877 A070878 A070879 * A070881 A070882 A070883


KEYWORD

easy,nonn


AUTHOR

Naohiro Nomoto, Nov 16 2003


EXTENSIONS

Edited by N. J. A. Sloane, Sep 09 2017
a(20)a(34) from Alois P. Heinz, Feb 08 2019


STATUS

approved



