login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A130754 A folded back triangular sequence of the binomial / Pascal's triangle A007318: half of the sequence is taken and doubled except for the odd middle terms which remain the same. 0
1, 2, 2, 2, 2, 6, 2, 4, 6, 2, 10, 20, 2, 6, 15, 20, 2, 14, 42, 70, 2, 8, 28, 56, 70, 2, 18, 72, 168, 252, 2, 10, 45, 120, 210, 252, 2, 22, 110, 330, 660, 924, 2, 12, 66, 220, 495, 792, 924, 2, 26, 156, 572, 1430, 2574, 3432, 2, 14, 91, 364, 1001, 2002, 3003, 3432, 2, 30 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This fold back operation leaves the row sums at 2^n.

LINKS

Table of n, a(n) for n=1..66.

FORMULA

a(n,i)== If[n > 0 && i == 0, 2, If[Mod[n, 2] == 0, binomial[n, i], 2*binomial[n, i]]];

EXAMPLE

{1},

{2},

{2, 2},

{2, 6},

{2, 4, 6},

{2, 10, 20},

{2, 6, 15, 20},

{2, 14, 42, 70},

{2, 8, 28, 56, 70},

{2, 18, 72, 168, 252},

{2, 10, 45, 120, 210, 252}

MATHEMATICA

f[n_, i_] = If[n > 0 && i == 0, 2, If[Mod[n, 2] == 0, Binomial[n, i], 2*Binomial[n, i]]]; Table[Table[f[n, i], {i, 0, Floor[n/2]}], {n, 0, 20}]; Flatten[%]

CROSSREFS

Cf. A007318.

Sequence in context: A070877 A156717 A198889 * A164126 A261902 A163368

Adjacent sequences:  A130751 A130752 A130753 * A130755 A130756 A130757

KEYWORD

nonn,tabf

AUTHOR

Roger L. Bagula, Jul 13 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 23 12:43 EDT 2019. Contains 321430 sequences. (Running on oeis4.)