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A157343 Triangle T(n,k) read by rows: T(n,k)=1 if the row index n is prime or <=1, otherwise T(n,k) = T(n-1,k)+T(n-1,k-1). 0
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 1, 1, 3, 4, 4, 4, 4, 4, 4, 3, 1, 1, 4, 7, 8, 8, 8, 8, 8, 7, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,12

COMMENTS

Row sums are: 1, 2, 3, 4, 8, 6, 12, 8, 16, 32, 64, 12, 24, 14, 28, 56,...

LINKS

Table of n, a(n) for n=0..104.

EXAMPLE

1;

1, 1;

1, 1, 1;

1, 1, 1, 1;

1, 2, 2, 2, 1;

1, 1, 1, 1, 1, 1;

1, 2, 2, 2, 2, 2, 1;

1, 1, 1, 1, 1, 1, 1, 1;

1, 2, 2, 2, 2, 2, 2, 2, 1;

1, 3, 4, 4, 4, 4, 4, 4, 3, 1;

1, 4, 7, 8, 8, 8, 8, 8, 7, 4, 1;

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;

1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1;

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;

1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1;

1, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 1;

MATHEMATICA

Clear[p, x, n, a];

p[x, 0] = 1; p[x, 1] = ((x + 1)); p[x, 2] = ((x^2 + x + 1));

p[x_, n_] := p[x, n] = If[PrimeQ[n], Sum[x^i, {i, 0, n}], (x + 1)*p[x, n - 1]];

a = Table[CoefficientList[FullSimplify[p[x, n]], x], {n, 0, 15}];

Flatten[a]

CROSSREFS

Sequence in context: A030597 A030599 A237413 * A102679 A025146 A067397

Adjacent sequences:  A157340 A157341 A157342 * A157344 A157345 A157346

KEYWORD

nonn,tabl,easy

AUTHOR

Roger L. Bagula, Feb 27 2009

STATUS

approved

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Last modified August 7 23:50 EDT 2022. Contains 355995 sequences. (Running on oeis4.)