A117607 Integer complexity of n represented with {1,+,!} and parentheses, where ! can be concatenated for multifactorials.
1, 2, 3, 4, 5, 3, 4, 4, 5, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 6, 4, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 3, 4, 5, 5
Offset: 1
Keywords
Examples
a(1) = 1 because there is one 1 in "1". a(2) = 2 because "1 + 1". a(6) = 3 because "(1+1+1)!". a(7) = 4 because "(1+1+1)!+1". a(8) = 4 because "(1+1+1+1)!!" using double factorial. a(12) = 3 because "((1+1+1)!)!!!!" using quadruple factorial. a(15) = 5 because "(1+1+1+1+1)!!" using double factorial. a(16) = 4 because "((1+1+1+1)!!)!!!!!!" using double factorial and sextuple factorial. a(24) = 3 because "(((1+1+1)!)!!!!)!!!!!!!!!!" using quadruple factorial and decuple factorial. a(36) = 3 because "(((1+1+1)!)!!!!)!!!!!!!!!" using quadruple factorial and nonuple factorial.
Links
- Ed Pegg, Jr., Integer Complexity
- Eric Weisstein's World of Mathematics, Multifactorial.
- Index to sequences related to the complexity of n
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