A319201
Expansion of f(t) = F^{[-1]}(t)/t, where F(x) = x/(1 - x^2 - x^3).
Original entry on oeis.org
1, 0, -1, -1, 2, 5, -2, -21, -14, 72, 138, -165, -803, -143, 3575, 4732, -11674, -36244, 15130, 195738, 152456, -799102, -1700272, 2042975, 11038183, 2582670, -53547795, -76684530, 185864265, 618689190, -231325605, -3506922585, -2974386450, 14866619160, 33459332610, -38401746930, -223156727472
Offset: 0
a(8) = (1/9)*[x^8] (1- x^2 - x^3)^9 = (1/9)*(-126) = -14.
a(8) = (1/9)*(- 9!/(6!*1!*2!) + 9!/(5!*0!*4!)) = -14, from the two solutions for [e2, e3], namely [1, 2] (parity odd) and [0, 4] (parity even).
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f := series(x/(1 - x^2 -x^3), x, 40):
r := gfun:-seriestoseries(f, 'revogf'):
gf := convert(r, polynom) / x:
seq(coeff(gf,x,n), n=0..36); # Peter Luschny, Nov 09 2018
A365730
G.f. satisfies A(x) = 1 + x^4*A(x)^4*(1 + x*A(x)).
Original entry on oeis.org
1, 0, 0, 0, 1, 1, 0, 0, 4, 9, 5, 0, 22, 78, 91, 35, 140, 680, 1224, 969, 1254, 5985, 14630, 17710, 17710, 55660, 164450, 269100, 299520, 593775, 1805076, 3681405, 4951692, 7594752, 20173560, 47303520, 76404460, 110676324, 239784864, 589602585, 1106339923
Offset: 0
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a(n) = sum(k=0, n\4, binomial(k, n-4*k)*binomial(n+1, k))/(n+1);
A365724
G.f. satisfies A(x) = 1 + x^3*A(x)^3*(1 + x*A(x)).
Original entry on oeis.org
1, 0, 0, 1, 1, 0, 3, 7, 4, 12, 45, 55, 77, 286, 546, 728, 1960, 4760, 7548, 15504, 39729, 75582, 140448, 336490, 723327, 1366200, 2992990, 6758895, 13522275, 28094040, 63183315, 133231800, 273896532, 600805296, 1305229332, 2720740792, 5843241088, 12797739672
Offset: 0
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a(n) = sum(k=0, n\3, binomial(k, n-3*k)*binomial(n+1, k))/(n+1);
A176806
Consider asymmetric 1-D random walk with set of possible jumps {-1,+1,+2}. Sequence gives number of paths of length n ending at origin.
Original entry on oeis.org
1, 0, 2, 3, 6, 20, 35, 105, 238, 588, 1512, 3630, 9339, 23166, 58487, 148148, 373230, 949416, 2406248, 6122142, 15591856, 39729000, 101432982, 259049230, 662421643, 1695149220, 4341026900, 11125755615, 28530984915, 73213888650, 187980163110, 482906682675
Offset: 0
a(3) = 3: (+2-1-1) or (-1+2-1) or (-1-1+2).
From _Wolfdieter Lang_, Nov 05 2018: (Start)
a(8) = (1/8!)*(d/dt)^8 (1 + t^2 + t^3)^8 becomes for t = 0: 238. (See the comment with the conjecture by _Joerg Arndt_, now proved.)
a(8) = 168 + 70 = 238, the row sum of row n = 8 of A321203, arising from the two [e2, e3] pairs [1, 2] and [4, 0], given in row n = 8 of A321201.
(End)
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a:=n->add(binomial(n,k)*binomial(k,3*k-n),k=floor((n+2)/3)..floor(n/2));
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Table[Sum[Binomial[n, k]*Binomial[k, 3*k-n], {k, Floor[(n+2)/3], Floor[n/2]}], {n, 0, 30}] (* Vaclav Kotesovec, Mar 01 2016 *)
A321196
Riordan triangle T = (1/(1 + x^2 - x^3), x/(1 + x^2 - x^3)).
Original entry on oeis.org
1, 0, 1, -1, 0, 1, 1, -2, 0, 1, 1, 2, -3, 0, 1, -2, 3, 3, -4, 0, 1, 0, -6, 6, 4, -5, 0, 1, 3, -1, -12, 10, 5, -6, 0, 1, -2, 12, -4, -20, 15, 6, -7, 0, 1, -3, -7, 30, -10, -30, 21, 7, -8, 0, 1, 5, -16, -15, 60, -20, -42, 28, 8, -9, 0, 1
Offset: 0
The triangle T(n, k) begins:
n\k 0 1 2 3 4 5 6 7 8 9 10 ...
---------------------------------------------
0: 1
1: 0 1
2: -1 0 1
3: 1 -2 0 1
4: 1 2 -3 0 1
5: -2 3 3 -4 0 1
6: 0 -6 6 4 -5 0 1
7: 3 -1 -12 10 5 -6 0 1
8: -2 12 -4 -20 15 6 -7 0 1
9: -3 -7 30 -10 -30 21 7 -8 0 1
10: 5 -16 -15 60 -20 -42 28 8 -9 0 1
...
Cayley-Hamilton formula for the matrix TS(x) =[[x,-1,1], [1,0,0], [0,1,0]] with Det(TS(x)) = +1, sigma(3, 2) = +1, and Tr(TS(x)) = x. For n = 3: TS(x)^3 = R(1, x)*TS(x)^2 + (-R(0, x) + R(-1, x))*TS(x) + R(0, x)*1_3 = x*TS(x)^2 - TS(x) + 1_3. Compare this for x = -1 with r^3 = R(3)*r^2 + (-R(2) + R(1))*r + R(2)*1 = r^2 - r + 1, where r = 1/t = A192918, with the tribonacci constant t = A058265, and R(n) = A057597(n) = R(n-2, -1).
Recurrence: T(5, 2) = T(4, 1) - T(3, 2) + T(2, 2) = 1 -(-1) + 1 = 3.
Boas-Buck type recurrence with B = {0, -2, 3, ...}:
T(5, 2) = ((2+1)/(5-2))*(3*1 + (-2)*0 + 0*(-3)) = 1*3 = 3.
Z- and A-recurrence with A(n) = {1, 0, -1, 1, -1, ...} and Z(n) = A(n+1):
T(4, 0) = 0*T(3, 0) - 1*T(3, 1) + 1*T(3, 2) - 1*T(3, 3) = 0 + 2 + 0 - 1 = 1.
T(5, 2) = 1*T(4, 1) + 0*T(4, 2) - 1*T(4, 3) + 1*T(4, 4) = 2 + 0 + 0 + 1 = 3.
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T[n_, k_] /; 0 <= k <= n := T[n, k] = T[n - 1, k - 1] - T[n - 2, k] + T[n - 3, k]; T[0, 0] = 1; T[, ] = 0;
Table[T[n, k], {n, 0, 10}, {k, 0, n}] (* Jean-François Alcover, Jul 06 2019 *)
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# uses[riordan_array from A256893]
riordan_array(1/(1 + x^2 - x^3), x/(1 + x^2 - x^3), 11) # Peter Luschny, Nov 13 2018
A321198
Triangular Riordan matrix T = R^(-1) for triangular Riordan matrix R = (1/(1 + x^2 - x^3), x/(1 + x^2 - x^3)) given in A321196.
Original entry on oeis.org
1, 0, 1, 1, 0, 1, -1, 2, 0, 1, 2, -2, 3, 0, 1, -5, 5, -3, 4, 0, 1, 8, -12, 9, -4, 5, 0, 1, -21, 21, -21, 14, -5, 6, 0, 1, 42, -56, 40, -32, 20, -6, 7, 0, 1, -96, 114, -108, 66, -45, 27, -7, 8, 0, 1, 222, -270, 225, -180, 100, -60, 35, -8, 9, 0, 1
Offset: 0
The triangle begins:
n\k 0 1 2 3 4 5 6 7 8 9 10 ...
-----------------------------------------------------------
0: 1
1: 0 1
2: 1 0 1
3: -1 2 0 1
4: 2 -2 3 0 1
5: -5 5 -3 4 0 1
6: 8 -12 9 -4 5 0 1
7: -21 21 -21 14 -5 6 0 1
8: 42 -56 40 -32 20 -6 7 0 1
9: -96 114 -108 66 -45 27 -7 8 0 1
10: 222 -270 225 -180 100 -60 35 -8 9 0 1
...
------------------------------------------------------------
Recurrence (from A- and Z-sequence): Z: T(5, 0) = T(4, 1) - T(4, 2) = -2 - 3 = -5. A: T(5, 2) = T(4, 1) + T(4, 3) - T(4, 4) = - 2 + 0 - 1 = -3.
Recurrence column k = 2 (Boas-Buck type sequence b = (-1)^(n+1)* = {0, 2, -3, 6, ...}): T(5, 2) = (3/3)*(b(2)*T(2, 2) + b(1)*T(3, 2) + b(0)*T(4, 2)) = -3*1 + 2*0 + 0*4 = -3.
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T[n_, k_] := T[n - 1, k - 1] + T[n - 1, k + 1] - T[n - 1, k + 2] /; n >= k >= 0;Table[T[n, k], {n, 0, 10}, {k, 0, n}] (* James C. McMahon, Dec 10 2023 *)
A321199
Row sums of Riordan triangle A321198.
Original entry on oeis.org
1, 1, 2, 2, 4, 2, 7, -5, 16, -40, 74, -196, 431, -999, 2433, -5575, 13600, -32264, 77794, -188630, 456078, -1113702, 2716432, -6656382, 16351231, -40236773, 99308252, -245471638, 608083547, -1508944093, 3750434282, -9336906118, 23277132752, -58112501728, 145266946742, -363574425058
Offset: 0
A321200
Alternating row sums of Riordan triangle A321198.
Original entry on oeis.org
1, -1, 2, -4, 8, -18, 39, -89, 204, -472, 1110, -2616, 6231, -14909, 35861, -86705, 210364, -512480, 1252350, -3069638, 7544818, -18589202, 45907708, -113608590, 281698359, -699748003, 1741102844, -4338995332, 10828981851, -27063384783, 67722954114, -169674183372, 425590855116, -1068654838488
Offset: 0
A321197
a(n) gives the A-sequence for the Riordan matrix (1/(1 + x^2 - x^3), x/(1 + x^2 - x^3)) from A321196.
Original entry on oeis.org
1, 0, -1, 1, -1, 3, -4, 10, -20, 42, -98, 210, -492, 1122, -2607, 6149, -14443, 34463, -82238, 197574, -476918, 1154402, -2807516, 6845016, -16743674, 41067512, -100967539, 248843095, -614546545, 1520779665
Offset: 0
A365609
G.f. satisfies A(x) = 1 + x^2*A(x)^4*(1 + x*A(x)).
Original entry on oeis.org
1, 0, 1, 1, 4, 9, 27, 78, 231, 715, 2193, 6954, 21999, 70840, 228896, 746650, 2447757, 8072208, 26745627, 89002364, 297344960, 996865397, 3352918429, 11310307593, 38256171642, 129718262583, 440855654827, 1501451066767, 5123671576890, 17516503865294
Offset: 0
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a(n) = sum(k=0, n\2, binomial(k, n-2*k)*binomial(n+2*k+1, k)/(n+2*k+1));
Showing 1-10 of 10 results.
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