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A244473 3rd-largest term in n-th row of Stern's diatomic triangle A002487. 2
1, 3, 5, 11, 18, 30, 49, 80, 129, 209, 338, 547, 885, 1432, 2317, 3749, 6066, 9815, 15881, 25696, 41577, 67273, 108850, 176123, 284973, 461096, 746069, 1207165, 1953234, 3160399, 5113633, 8274032, 13387665, 21661697, 35049362, 56711059, 91760421 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Colin Barker, Table of n, a(n) for n = 2..1000

Jennifer Lansing, Largest Values for the Stern Sequence, J. Integer Seqs., 17 (2014), #14.7.5.

Index entries for linear recurrences with constant coefficients, signature (1,1).

FORMULA

a(n) = a(n-1)+a(n-2) for n>9. - Colin Barker, Jul 10 2015

G.f.: -x^2*(x^7+x^6+x^5+2*x^4+3*x^3+x^2+2*x+1) / (x^2+x-1). - Colin Barker, Jul 10 2015

MAPLE

A244473 := proc(n)

    if n < 8 then

        op(n, [-1, 1, 3, 5, 11, 18, 30]) ;

    else

        combinat[fibonacci](n+1)+5*combinat[fibonacci](n-4) ;

    end if;

end proc:

seq(A244473(n), n=2..50) ; # R. J. Mathar, Jul 05 2014

MATHEMATICA

Join[{1, 3, 5, 11, 18, 30}, LinearRecurrence[{1, 1}, {49, 80}, 40]] (* Harvey P. Dale, Jan 13 2015 *)

PROG

(PARI) Vec(-x^2*(x^7+x^6+x^5+2*x^4+3*x^3+x^2+2*x+1)/(x^2+x-1) + O(x^100)) \\ Colin Barker, Jul 10 2015

CROSSREFS

Cf. A002487, A244472-A244476.

Sequence in context: A128949 A070316 A298121 * A023597 A281357 A320789

Adjacent sequences:  A244470 A244471 A244472 * A244474 A244475 A244476

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Jul 01 2014

STATUS

approved

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Last modified January 26 11:26 EST 2020. Contains 331279 sequences. (Running on oeis4.)