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A026022
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Triangular array T read by rows: T(n,0) = 1 for n >= 0; T(n,k) = C(n,k) for k = 1,2,...,n, for n = 1,2,3; and for n >= 4, T(n,k) = T(n-1,k-1) + T(n-1,k) for k = 1,2,...,[ (n+2)/2 ] and T(n,(n+3)/2) = T(n-1,(n+1)/2) if n is odd.
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15
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1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 6, 4, 1, 5, 10, 10, 4, 1, 6, 15, 20, 14, 1, 7, 21, 35, 34, 14, 1, 8, 28, 56, 69, 48, 1, 9, 36, 84, 125, 117, 48, 1, 10, 45, 120, 209, 242, 165, 1, 11, 55, 165, 329, 451, 407, 165, 1, 12, 66, 220, 494, 780, 858, 572, 1, 13, 78, 286, 714, 1274, 1638, 1430, 572
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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FORMULA
| T(n, k) = C(n, k) - C(n, k-4). - Ralf Stephan, Jan 09 2005
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EXAMPLE
| 1; 1, 1; 1, 2, 1; 1, 3, 3, 1; 1, 4, 6, 4; 1, 5, 10, 10, 4; 1, 6, 15, 20, 20; ...
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PROG
| (PARI) {T(n, k) = if( 2*k < n+4, binomial( n, k) - binomial( n, k-4), 0)} /* Michael Somos, Jan 08 2012 */
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CROSSREFS
| Sequence in context: A034253 A203952 A118687 * A073714 A171848 A144151
Adjacent sequences: A026019 A026020 A026021 * A026023 A026024 A026025
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KEYWORD
| nonn,tabl
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
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