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A173388 a(n) = a(n - 3) + a(n - 4) if n is even, else a(n - 2) + a(n - 3). 0
1, 1, 1, 1, 2, 2, 2, 4, 4, 6, 6, 10, 10, 16, 16, 26, 26, 42, 42, 68, 68, 110, 110, 178, 178, 288, 288, 466, 466, 754, 754, 1220, 1220, 1974, 1974, 3194, 3194, 5168, 5168, 8362, 8362, 13530, 13530, 21892, 21892, 35422, 35422, 57314, 57314, 92736, 92736 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

The sequence is designed so that all the numbers, see A055389 or A006355, except the first two appear twice.

The limiting ratio a(n+1)/a(n) alternates between the golden ratio and one.

Essentially the same as A214927 (except for the first 4 terms and the offset). - Georg Fischer, Oct 01 2018

LINKS

Table of n, a(n) for n=0..50.

FORMULA

a(n) = a(n-2)+a(n-4), n > 7.

G.f.: (x^7+1+x-x^6)/(1-x^2-x^4).

MATHEMATICA

a[0] = 1; a[1] = 1; a[2] = 1; a[3] = 1;

a[n_] := a[n] = If[Mod[n, 2] == 0, a[n - 3] + a[n - 4], a[n - 2] + a[n - 3]];

Table[a[n], {n, 0, 50}]

CROSSREFS

Sequence in context: A172068 A289195 A008331 * A326679 A326541 A326680

Adjacent sequences:  A173385 A173386 A173387 * A173389 A173390 A173391

KEYWORD

nonn,easy,less

AUTHOR

Roger L. Bagula, Feb 17 2010

EXTENSIONS

Formula added by the Assoc. Editors of the OEIS, Feb 24 2010

STATUS

approved

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Last modified October 21 23:34 EDT 2021. Contains 348160 sequences. (Running on oeis4.)