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A202337
Range of A062723.
3
1, 2, 6, 12, 36, 108, 324, 972, 2916, 8748, 26244, 78732, 236196, 708588, 2125764, 6377292, 19131876, 57395628, 172186884, 516560652, 1549681956, 4649045868, 13947137604, 41841412812, 125524238436, 376572715308, 1129718145924, 3389154437772, 10167463313316
OFFSET
1,2
COMMENTS
Subsequence of A000792.
Apparently a(n) = A052156(n - 1) for n >= 4. - Georg Fischer, Mar 26 2019
FORMULA
From Colin Barker, Mar 26 2019: (Start)
G.f.: x*(1 - x - 6*x^3) / (1 - 3*x).
a(n) = 4*3^(n-3) for n>3.
a(n) = 3*a(n-1) for n>4.
(End)
PROG
(Haskell)
a202337 n = a202337_list !! (n-1)
a202337_list = f a062723_list where
f (x:xs'@(x':xs)) = if x == x' then f xs' else x : f xs'
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Dec 17 2011
STATUS
approved