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A047904
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a(n+1) = a(n) + n (if n is odd), a(n+1) = a(n) * n (if n is even).
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4
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1, 2, 4, 7, 28, 33, 198, 205, 1640, 1649, 16490, 16501, 198012, 198025, 2772350, 2772365, 44357840, 44357857, 798441426, 798441445, 15968828900, 15968828921, 351314236262, 351314236285, 8431541670840, 8431541670865, 219220083442490
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..100
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MAPLE
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A047904:=proc(q)
local a, n; a:=1; print(a);
for n from 2 to q do a:=1/2*((n-1+a)*(1+(-1)^n)+a*(n-1)*(1-(-1)^n)); print(a); od; end:
A047904(1000); # Paolo P. Lava, Feb 19 2013
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MATHEMATICA
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Transpose[NestList[{#[[1]]+1, If[OddQ[#[[1]]], Total[#], Times@@#]}&, {1, 1}, 30]][[2]] (* Harvey P. Dale, Sep 11 2012 *)
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PROG
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(Python)
a=1
for n in range(1, 33):
print a,
if n&1:
a += n
else:
a *= n
# from Alex Ratushnyak, Feb 24 2013
(Haskell)
a047904 n = a047904_list !! (n-1)
a047904_list = 1 : zipWith
(\(op, i) x -> op i x) (zip (cycle [(+), (*)]) [1..]) a047904_list
-- Reinhard Zumkeller, Mar 24 2013
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CROSSREFS
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Cf. A000124, A047905, A077138.
Sequence in context: A222907 A179386 A065846 * A102118 A102119 A102121
Adjacent sequences: A047901 A047902 A047903 * A047905 A047906 A047907
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KEYWORD
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nonn,easy,nice
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AUTHOR
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Miklos SZABO (mike(AT)ludens.elte.hu)
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STATUS
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approved
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