A244473 3rd-largest term in n-th row of Stern's diatomic triangle A002487.

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

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