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Search: id:A152440
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| A152440 |
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Riordan matrix (1/(1-x-x^2),x/(1-x-x^2)^2) |
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+0
1
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| 1, 1, 1, 2, 3, 1, 3, 9, 5, 1, 5, 22, 20, 7, 1, 8, 51, 65, 35, 9, 1, 13, 111, 190, 140, 54, 11, 1, 21, 233, 511, 490, 255, 77, 13, 1, 34, 474, 1295, 1554, 1035, 418, 104, 15, 1, 55, 942, 3130, 4578, 3762, 1925, 637, 135, 17, 1, 89, 1836, 7285, 12720, 12573, 7865, 3276
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OFFSET
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0,4
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FORMULA
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a(n,k) = sum( binomial(n-j-k,2k) binomial(n-j-k,j), j=0...(n-k)/2 )
a(n,k) = sum( binomial(i+2k,2k) binomial(n-i+k,i+2k), i=0...(n - k)/2 )
Recurrence: a(n+4,k+1) - 2 a(n+3,k+1) - a(n+3,k) - a(n+2,k+1) + 2 a(n+1,k+1) + a(n,k+1) = 0
GF for columns: 1/(1-x-x^2)(x/(1-x-x^2)^2)^k
GF: (1-x-x^2)/((1-x-x^2)^2-xy)
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CROSSREFS
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The first row is given by A000045.
Sequence in context: A058127 A133935 A139633 this_sequence A134319 A135091 A111589
Adjacent sequences: A152437 A152438 A152439 this_sequence A152441 A152442 A152443
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KEYWORD
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easy,nonn,tabl
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AUTHOR
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Emanuele Munarini (emanuele.munarini(AT)polimi.it), Dec 04 2008, Dec 05 2008
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