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A131240 T(n,k) = 2*A046854(n,k) - I. 2
1, 2, 1, 2, 2, 1, 2, 4, 2, 1, 2, 4, 6, 2, 1, 2, 6, 6, 8, 2, 1, 2, 6, 12, 8, 10, 2, 1, 2, 8, 12, 20, 10, 12, 2, 1, 2, 8, 20, 20, 30, 12, 14, 2, 1, 2, 10, 20, 40, 30, 42, 14, 16, 2, 1, 2, 10, 30, 40, 70, 42, 56, 16, 18, 2, 1, 2, 12, 30, 70, 70, 112, 56, 72, 18, 20, 2, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Row sums = A001595: (1, 3, 5, 9, 15, 25, 41, 67,...).

A131241 = 3*A046854 - 2*I.

LINKS

G. C. Greubel, Rows n = 0..100 of triangle, flattened

FORMULA

T(n,k) = 2*A046854(n,k) - Identity matrix, where A046854 = Pascal's triangle with repeats by columns.

EXAMPLE

First few rows of the triangle are:

  1;

  2, 1;

  2, 2,  1;

  2, 4,  2, 1;

  2, 4,  6, 2,  1;

  2, 6,  6, 8,  2, 1;

  2, 6, 12, 8, 10, 2, 1; ...

MATHEMATICA

Table[If[k==n, 1, 2*Binomial[Floor[(n+k)/2], k]], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, Jul 12 2019 *)

PROG

(PARI) T(n, k) = if(k==n, 1, 2*binomial((n+k)\2, k));

(MAGMA) [k eq n select 1 else 2*Binomial(Floor((n+k)/2), k): k in [0..n], n in [0..12]]; // G. C. Greubel, Jul 12 2019

(Sage)

def T(n, k):

    if (k==n): return 1

    else: return 2*binomial(floor((n+k)/2), k)

[[T(n, k) for k in (0..n)] for n in (0..12)] # G. C. Greubel, Jul 12 2019

(GAP)

T:= function(n, k)

    if k=n then return 1;

    else return 2*Binomial(Int((n+k)/2), k);

    fi;

  end;

Flat(List([0..12], n-> List([0..n], k-> T(n, k)))); # G. C. Greubel, Jul 12 2019

CROSSREFS

Cf. A001595, A046854, A131241.

Sequence in context: A140186 A078498 A178522 * A263666 A107027 A107030

Adjacent sequences:  A131237 A131238 A131239 * A131241 A131242 A131243

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Jun 21 2007

EXTENSIONS

More terms added by G. C. Greubel, Jul 12 2019

STATUS

approved

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Last modified April 17 03:58 EDT 2021. Contains 343059 sequences. (Running on oeis4.)