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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified October 22 10:24 EDT 2019. Contains 328317 sequences. (Running on oeis4.)