A227356 Partial sums of A129361.

1, 2, 5, 10, 20, 36, 65, 112, 193, 324, 544, 900, 1489, 2442, 4005, 6534, 10660, 17336, 28193, 45760, 74273, 120408, 195200, 316216, 512257, 829458, 1343077, 2174130, 3519412, 5696124, 9219105, 14919408, 24144289

Offset

1,2

Comments

Sum of labeled numbers of boxes arranged as Pyramid type-II with base Fibonacci(n).

Let us call a Pyramid "type-I" when each row starts with the same number as the leftmost base number, and "type-II" when each column has the same number as the base.

The Pyramid arrangements are related to other sequences as follows:

Base Number Type-I Type-II

----------- ------ -------

Natural A002623 A034828

Odd A000292 A128624

Fibonacci A129696 a(n)

1 A002620 A002620

1,0 A008805

See illustration in links.

Links

Table of n, a(n) for n=1..33.

Kival Ngaokrajang, Illustration for some small n.

Index entries for linear recurrences with constant coefficients, signature (2,1,-3,1,-1,0,1).

Formula

For n >=2, a(n) = a(n-1) + A129361(n-1).

G.f. -x*(1+x)*(x^2-x+1) / ( (x-1)*(x^2+x-1)*(x^4+x^2-1) ). - Joerg Arndt, Jul 10 2013

a(n) = 2 + A000045(n+4) - A096748(n+6). - R. J. Mathar, Jul 20 2013

Prog

(Small Basic)
a[1] = 1
k = 0
s5 = Math.SquareRoot(5)
For n = 2 To 51
  If Math.Remainder(n, 2)=0 Then
    i = (n+2)/2
  Else
    i = (n+1)/2
  EndIf
  For j = i To n
    k = k + Math.Round(Math.Power((1+s5)/2, j)/s5)
  EndFor
  a[n] = a[n-1] + k
  TextWindow.Write(a[n-1] + ", ")
  k = 0
EndFor

Crossrefs

Cf. A002623, A034828, A002620, A000292, A128624, A129696, A008805.

Sequence in context: A327292 A327291 A327290 * A327289 A327288 A102688

Adjacent sequences: A227353 A227354 A227355 * A227357 A227358 A227359

Keyword

nonn

Author

Kival Ngaokrajang, Jul 08 2013

Status

approved