

A138651


Number of distinct values obtained when each of the operators # in the expression 1#2#3#...#n is replaced by + (add) or x (multiply) in all possible ways, for n=1,2,3,...


0



1, 2, 3, 7, 14, 26, 52, 104, 201, 379, 751, 1422, 2679, 5068, 9383, 17249, 31285, 57171, 103476, 186921, 333991, 594921, 1044076, 1837839, 3198889, 5561453
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..26.


EXAMPLE

For n=4, the eight expressions {1+2+3+4,1+2+3x4,1+2x3+4,1+2x3x4,1x2+3+4,1x2+3x4, 1x2x3+4,1x2x3x4} are obtained, with the eight values {10,15,11,25,9,14,10,24} respectively, seven of which are distinct, so a(4)=7.


CROSSREFS

Cf. A069765, A078389.
Sequence in context: A027957 A300569 A054194 * A131300 A078043 A294627
Adjacent sequences: A138648 A138649 A138650 * A138652 A138653 A138654


KEYWORD

nonn,more


AUTHOR

John W. Layman, May 15 2008


EXTENSIONS

More terms (17..26) from Wojciech Florek, Feb 27 2018


STATUS

approved



