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 A155997 Triangle read by rows: T(n, k) = f(n, k) + f(n, n-k), where f(n, k) = binomial(n, k)*(1 + (-1)^k)/2. 1
 2, 1, 1, 2, 0, 2, 1, 3, 3, 1, 2, 0, 12, 0, 2, 1, 5, 10, 10, 5, 1, 2, 0, 30, 0, 30, 0, 2, 1, 7, 21, 35, 35, 21, 7, 1, 2, 0, 56, 0, 140, 0, 56, 0, 2, 1, 9, 36, 84, 126, 126, 84, 36, 9, 1, 2, 0, 90, 0, 420, 0, 420, 0, 90, 0, 2, 1, 11, 55, 165, 330, 462, 462, 330, 165, 55, 11, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Row sums are: {2, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024,...} LINKS G. C. Greubel, Rows n = 0..100 of triangle, flattened FORMULA T(n, k) = f(n, k) + f(n, n-k), where f(n, k) = binomial(n, k)*(1 + (-1)^k)/2. From G. C. Greubel, Dec 01 2019: (Start) T(n, k) = binomial(n, k)*(2 + (-1)^k*(1 + (-1)^n))/2. Sum_{k=0..n} T(n,k) = 2^n for n >= 1. Sum_{k=0..n-1} T(n,k) = (2^(n+1) - 3 - (-1)^n)/2 = A140253(n), n >= 2. (End) EXAMPLE Triangle begins as:   2;   1, 1;   2, 0,  2;   1, 3,  3,  1;   2, 0, 12,  0,   2;   1, 5, 10, 10,   5,   1;   2, 0, 30,  0,  30,   0,   2;   1, 7, 21, 35,  35,  21,   7,  1;   2, 0, 56,  0, 140,   0,  56,  0,  2;   1, 9, 36, 84, 126, 126,  84, 36,  9, 1;   2, 0, 90,  0, 420,   0, 420,  0, 90, 0, 2; MAPLE seq(seq( binomial(n, k)*(2+(-1)^k*(1+(-1)^n))/2, k=0..n), n=0..12); # G. C. Greubel, Dec 01 2019 MATHEMATICA f[n_, k_]:= (Binomial[n, k] + (-1)^k*Binomial[n, k])/2; Table[f[n, k]+f[n, n-k], {n, 0, 10}, {k, 0, n}]//Flatten Table[Binomial[n, k]*(2+(-1)^k*(1+(-1)^n))/2, {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, Dec 01 2019 *) PROG (PARI) T(n, k) = binomial(n, k)*(2 + (-1)^k*(1 + (-1)^n))/2; \\ G. C. Greubel, Dec 01 2019 (MAGMA) [Binomial(n, k)*(2+(-1)^k*(1+(-1)^n))/2: k in [0..n], n in [0..12]]; // G. C. Greubel, Dec 01 2019 (Sage) [[binomial(n, k)*(2+(-1)^k*(1+(-1)^n))/2 for k in (0..n)] for n in (0..12)] # G. C. Greubel, Dec 01 2019 (GAP) Flat(List([0..12], n-> List([0..n], k-> Binomial(n, k)*(2 + (-1)^k*(1 + (-1)^n))/2 ))); # G. C. Greubel, Dec 01 2019 CROSSREFS Sequence in context: A194529 A055138 A177717 * A326171 A123223 A088226 Adjacent sequences:  A155994 A155995 A155996 * A155998 A155999 A156000 KEYWORD nonn,tabl,changed AUTHOR Roger L. Bagula, Feb 01 2009 STATUS approved

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Last modified December 14 19:27 EST 2019. Contains 329987 sequences. (Running on oeis4.)