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A124925 Interlaced triples: a(3n+1)=1. a(3n+2) = 2n+3. a(3n+3)= A028387(n). 0
1, 3, 1, 1, 5, 5, 1, 7, 11, 1, 9, 19, 1, 11, 29, 1, 13, 41, 1, 15, 55, 1, 17, 71, 1, 19, 89, 1, 21, 109, 1, 23, 131, 1, 25, 155, 1, 27, 181, 1, 29, 209, 1, 31, 239, 1, 33, 271, 1, 35, 305, 1, 37, 341, 1, 39, 379, 1, 41, 419, 1, 43, 461, 1, 45, 505, 1, 47, 551, 1, 49, 599, 1, 51, 649, 1, 53 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Three consecutive terms of the sequence define a polynomial a(3n+1)*x^2 - a(3n+2)*x +a(3n+3) which has a root x= 1 +n + golden ratio.

LINKS

Table of n, a(n) for n=1..77.

FORMULA

a(n)= 3*a(n-3) -3*a(n-6) +a(n-9).

G.f.: x*(-1-3*x-x^2+2*x^3+4*x^4-2*x^5-x^6-x^7+x^8) / ((x-1)^3 * (1+x+x^2)^3 ).

CROSSREFS

Cf. A001622.

Sequence in context: A108553 A176700 A158418 * A073145 A245368 A239331

Adjacent sequences:  A124922 A124923 A124924 * A124926 A124927 A124928

KEYWORD

nonn,easy,less

AUTHOR

Gary W. Adamson, Nov 12 2006

EXTENSIONS

Edited and extended by R. J. Mathar, Mar 28 2010

STATUS

approved

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Last modified February 24 18:24 EST 2018. Contains 299628 sequences. (Running on oeis4.)