A035513 Wythoff array read by falling antidiagonals.
1, 2, 4, 3, 7, 6, 5, 11, 10, 9, 8, 18, 16, 15, 12, 13, 29, 26, 24, 20, 14, 21, 47, 42, 39, 32, 23, 17, 34, 76, 68, 63, 52, 37, 28, 19, 55, 123, 110, 102, 84, 60, 45, 31, 22, 89, 199, 178, 165, 136, 97, 73, 50, 36, 25, 144, 322, 288, 267, 220, 157, 118, 81, 58, 41, 27, 233, 521
Offset: 1
A022086 Fibonacci sequence beginning 0, 3.
0, 3, 3, 6, 9, 15, 24, 39, 63, 102, 165, 267, 432, 699, 1131, 1830, 2961, 4791, 7752, 12543, 20295, 32838, 53133, 85971, 139104, 225075, 364179, 589254, 953433, 1542687, 2496120, 4038807, 6534927, 10573734, 17108661, 27682395, 44791056, 72473451, 117264507
Offset: 0
Comments
First differences of A111314. - Ross La Haye, May 31 2006
Pisano period lengths: 1, 3, 1, 6, 20, 3, 16, 12, 8, 60, 10, 6, 28, 48, 20, 24, 36, 24, 18, 60, ... . - R. J. Mathar, Aug 10 2012
For n>=6, a(n) is the number of edge covers of the union of two cycles C_r and C_s, r+s=n, with a single common vertex. - Feryal Alayont, Oct 17 2024
References
- A. T. Benjamin and J. J. Quinn, Proofs that really count: the art of combinatorial proof, M.A.A. 2003, id. 7,17.
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- Tanya Khovanova, Recursive Sequences
- Index entries for linear recurrences with constant coefficients, signature (1,1).
Crossrefs
Programs
-
Magma
[3*Fibonacci(n): n in [0..40]]; // Vincenzo Librandi, Dec 31 2016
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Maple
BB := n->if n=0 then 3; > elif n=1 then 0; > else BB(n-2)+BB(n-1); > fi: > L:=[]: for k from 1 to 34 do L:=[op(L),BB(k)]: od: L; # Zerinvary Lajos, Mar 19 2007 with (combinat):seq(sum((fibonacci(n,1)),m=1..3),n=0..32); # Zerinvary Lajos, Jun 19 2008
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Mathematica
LinearRecurrence[{1, 1}, {0, 3}, 40] (* Arkadiusz Wesolowski, Aug 17 2012 *) Table[Fibonacci[n + 4] + Fibonacci[n - 4] - 4 Fibonacci[n], {n, 0, 40}] (* Bruno Berselli, Dec 30 2016 *) Table[3 Fibonacci[n], {n, 0, 40}] (* Vincenzo Librandi, Dec 31 2016 *)
-
PARI
a(n)=3*fibonacci(n) \\ Charles R Greathouse IV, Nov 06 2014
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SageMath
def A022086(n): return 3*fibonacci(n) print([A022086(n) for n in range(41)]) # G. C. Greubel, Apr 10 2025
Formula
a(n) = 3*Fibonacci(n).
a(n) = F(n-2) + F(n+2) for n>1, with F=A000045.
a(n) = round( ((6*phi-3)/5) * phi^n ) for n>2. - Thomas Baruchel, Sep 08 2004
a(n) = A119457(n+1,n-1) for n>1. - Reinhard Zumkeller, May 20 2006
G.f.: 3*x/(1-x-x^2). - Philippe Deléham, Nov 19 2008
a(n) = A187893(n) - 1. - Filip Zaludek, Oct 29 2016
E.g.f.: 6*sinh(sqrt(5)*x/2)*exp(x/2)/sqrt(5). - Ilya Gutkovskiy, Oct 29 2016
a(n) = F(n+4) + F(n-4) - 4*F(n), F = A000045. - Bruno Berselli, Dec 29 2016
A267633 Expansion of (1 - 4t)/(1 - x + t x^2): a Fibonacci-type sequence of polynomials.
1, -4, 1, -4, 1, -5, 4, 1, -6, 8, 1, -7, 13, -4, 1, -8, 19, -12, 1, -9, 26, -25, 4, 1, -10, 34, -44, 16, 1, -11, 43, -70, 41, -4, 1, -12, 53, -104, 85, -20, 1, -13, 64, -147, 155, -61, 4, 1, -14, 76, -200, 259, -146, 24
Offset: 0
Examples
Row polynomials: P(0,t) = 1 - 4t P(1,t) = 1 - 4t = [-t(0) + (1-4t)] = -t(0) + P(0,t) P(2,t) = 1 - 5t + 4t^2 = [-t(1-4t) + (1-4t)] = -t P(0,t) + P(1,t) P(3,t) = 1 - 6t + 8t^2 = [-t(1-4t) + (1-5t+4t^2)] = -t P(1,t) + P(2,t) P(4,t) = 1 - 7t + 13t^2 - 4t^3 = [-t(1-5t+4t^2) + (1-6t+8t^2)] P(5,t) = 1 - 8t + 19t^2 - 12t^3 = [-t(1-6t+8t^2) + (1-7t+13t^2)] P(6,t) = 1 - 9t + 26t^2 - 25t^3 + 4t^4 P(7,t) = 1 - 10t + 34t^2 - 44t^3 + 16t^4 P(8,t) = 1 - 11t + 43t^2 - 70t^3 + 41t^4 - 4t^5 P(9,t) = 1 - 12t + 53t^2 - 104t^3 + 85t^4 - 20t^5 P(10,t) = 1 - 13t + 64t^2 - 147t^3 + 155t^4 - 61t^5 + 4t^6 P(11,t) = 1 - 14t + 76t^2 - 200t^3 + 259t^4 - 146t^5 + 24t^6 ... Apparently: The odd rows for n>1 are reversed rows of A140882 (mod signs), and the even rows for n>0, the 9th, 15th, 21st, 27th, etc. rows of A228785 (mod signs). The diagonals are reverse rows of A202241.
Links
- Tom Copeland, Addendum to Elliptic Lie Triad
Crossrefs
Programs
-
Mathematica
p = (1 - 4 t) / (1 - x + t x^2) + O[x]^12 // CoefficientList[#, x] &; CoefficientList[#, t] & /@ p // Flatten (* Andrey Zabolotskiy, Mar 07 2024 *)
Formula
O.g.f. G(x,t) = (1 - 4t)/(1 - x + t x^2) = a / [t (x - (1+sqrt(a))/(2t))(x - (1-sqrt(a))/(2t))] with a = 1-4t.
Recursion P(n,t) = -t P(n-2,t) + P(n-1,t) with P(-1,t)=0 and P(0,t) = 1-4t.
Convolution of the Fibonacci polynomials of signed A011973 Fb(n,-t) with coefficients of (1-4t), e.g., (1-4t)Fb(5,-t) = (1-4t)(1-3t+t^2) = 1-7t+13t^2-4t^3, so, for n>=1 and k<=(n-1), T(n,k) = (-1)^k [-4*binomial(n-(k-1),k-1) - binomial(n-k,k)] with the convention that 1/(-m)! = 0 for m>=1, i.e., let binomial(n,k) = nint[n!/((k+c)!(n-k+c)!)] for c sufficiently small in magnitude.
Third column is A034856, and the fourth, A000297. Embedded in the coefficients of the highest order term of the polynomials is A008586 (cf. also A008574).
With P(0,t)=0, the o.g.f. is H(x,t) = (1-4t) x(1-tx)/[1-x(1-tx)] = (1-4t) Linv(Cinv(tx)/t), where Linv(x) = x/(1-x) with inverse L(x) = x/(1+x) and Cinv(x) = x (1-x) is the inverse of the o.g.f. of the shifted Catalan numbers A000108, C(x) = [1-sqrt(1-4x)]/2. Then Hinv(x,t) = C[t L(x/(1-4t))]/t = {1 - sqrt[1-4t(x/(1-4t))/[1+x/(1-4t)]]}/2t = {1-sqrt[1-4tx/(1-4t+x)]}/2t = 1/(1-4t) + (-1+t)/(1-4t)^2 x + (1-2t+2t^2)/(1-4t)^3 x^ + (-1+3t-6t^2+5t^3)/(1-4t)^4 + ..., where the numerators are the signed polynomials of A098474, reverse of A124644.
Row sums (t=1) are periodic -3,-3,0,3,3,0, repeat the six terms ... with o.g.f. -3 - 3x (1-x) / [1-x(1-x)]. Cf. A084103.
Unsigned row sums (t=-1) are shifted A022088 with o.g.f. 5 + 5x(1+x) / [x(1+x)].
Extensions
Data corrected by Andrey Zabolotskiy, Mar 07 2024
A119457 Triangle read by rows: T(n, 1) = n, T(n, 2) = 2*(n-1) for n>1 and T(n, k) = T(n-1, k-1) + T(n-2, k-2) for 2 < k <= n.
1, 2, 2, 3, 4, 3, 4, 6, 6, 5, 5, 8, 9, 10, 8, 6, 10, 12, 15, 16, 13, 7, 12, 15, 20, 24, 26, 21, 8, 14, 18, 25, 32, 39, 42, 34, 9, 16, 21, 30, 40, 52, 63, 68, 55, 10, 18, 24, 35, 48, 65, 84, 102, 110, 89, 11, 20, 27, 40, 56, 78, 105, 136, 165, 178, 144, 12, 22, 30, 45, 64, 91, 126, 170, 220, 267, 288, 233
Offset: 1
Examples
Triangle begins as: 1; 2, 2; 3, 4, 3; 4, 6, 6, 5; 5, 8, 9, 10, 8; 6, 10, 12, 15, 16, 13; 7, 12, 15, 20, 24, 26, 21; 8, 14, 18, 25, 32, 39, 42, 34; 9, 16, 21, 30, 40, 52, 63, 68, 55; 10, 18, 24, 35, 48, 65, 84, 102, 110, 89; 11, 20, 27, 40, 56, 78, 105, 136, 165, 178, 144; 12, 22, 30, 45, 64, 91, 126, 170, 220, 267, 288, 233;
Links
- G. C. Greubel, Rows n = 1..50 of the triangle, flattened
- Eric Weisstein's World of Mathematics, Fibonacci Number
Crossrefs
Main diagonal: A023607(n).
Columns: A000027(n) (k=1), A005843(n-1) (k=2), A008585(n-2) (k=3), A008587(n-3) (k=4), A008590(n-4) (k=5), A008595(n-5) (k=6), A008603(n-6) (k=7).
Programs
-
Magma
A119457:= func< n,k | (n-k+1)*Fibonacci(k+1) >; [A119457(n,k): k in [1..n], n in [1..12]]; // G. C. Greubel, Apr 16 2025
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Mathematica
(* First program *) T[n_, 1] := n; T[n_ /; n > 1, 2] := 2 n - 2; T[n_, k_] /; 2 < k <= n := T[n, k] = T[n - 1, k - 1] + T[n - 2, k - 2]; Table[T[n, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Jean-François Alcover, Dec 01 2021 *) (* Second program *) A119457[n_,k_]:= (n-k+1)*Fibonacci[k+1]; Table[A119457[n,k], {n,13}, {k,n}]//Flatten (* G. C. Greubel, Apr 16 2025 *)
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SageMath
def A119457(n,k): return (n-k+1)*fibonacci(k+1) print(flatten([[A119457(n,k) for k in range(1,n+1)] for n in range(1,13)])) # G. C. Greubel, Apr 16 2025
Formula
T(n, k) = (n-k+1)*T(k,k) for 1 <= k < n, with T(n, n) = A000045(n+1).
From G. C. Greubel, Apr 15 2025: (Start)
T(n, k) = (n-k+1)*Fibonacci(k+1).
A280154 a(n) = 5*Lucas(n).
10, 5, 15, 20, 35, 55, 90, 145, 235, 380, 615, 995, 1610, 2605, 4215, 6820, 11035, 17855, 28890, 46745, 75635, 122380, 198015, 320395, 518410, 838805, 1357215, 2196020, 3553235, 5749255, 9302490, 15051745, 24354235, 39405980, 63760215, 103166195, 166926410, 270092605, 437019015
Offset: 0
Comments
Fibonacci sequence beginning 10, 5.
After 5, the sequence provides the 3rd column of the rectangular array in A213590.
After 5, all terms belong to A191921 because a(n) = Lucas(n+4) - 3*Lucas(n-1).
From G. C. Greubel, Dec 27 2016: (Start)
{a(n) mod 3} yields (1,2,0,2,2,1,0,1), repeated, and is given as A082115.
{a(n) mod 6} yields (4,5,3,2,5,1,0,1,1,2,3,5,2,1,3,4,1,5,0,5,5,4,3,1) and is given as A082117. (End)
Links
- Bruno Berselli, Table of n, a(n) for n = 0..1000
- Tanya Khovanova, Recursive Sequences
- Index entries for linear recurrences with constant coefficients, signature (1,1).
Crossrefs
Programs
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Magma
[5*Lucas(n): n in [0..40]];
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Maple
F := n -> combinat:-fibonacci(n): seq(F(n+5) + F(n-5), n=0..38); # Peter Luschny, Dec 29 2016
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Mathematica
Table[5 LucasL[n], {n, 0, 40}]
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PARI
vector(40, n, n--; fibonacci(n+5)+fibonacci(n-5))
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Sage
def A280154(): x, y = 10, 5 while True: yield x x, y = y, x + y a = A280154(); print([next(a) for in range(39)]) # _Peter Luschny, Dec 29 2016
Formula
G.f.: 5*(2 - x)/(1 - x - x^2).
a(n) = a(n-1) + a(n-2) for n>1.
a(n) = Fibonacci(n+5) + Fibonacci(n-5), with Fibonacci(-k) = -(-1)^k*Fibonacci(k) for the negative indices.
A126714 Dual Wythoff array read along antidiagonals.
1, 2, 4, 3, 6, 7, 5, 10, 11, 9, 8, 16, 18, 14, 12, 13, 26, 29, 23, 19, 15, 21, 42, 47, 37, 31, 24, 17, 34, 68, 76, 60, 50, 39, 27, 20, 55, 110, 123, 97, 81, 63, 44, 32, 22, 89, 178, 199, 157, 131, 102, 71, 52, 35, 25, 144, 288, 322, 254, 212, 165, 115, 84, 57, 40, 28
Offset: 1
Comments
The dual Wythoff array is the dispersion of the sequence w given by w(n)=2+floor(n*x), where x=(golden ratio), so that w=2+A000201(n). For a discussion of dispersions, see A191426. - Clark Kimberling, Jun 03 2011
Examples
Array starts 1 2 3 5 8 13 21 34 55 89 144 4 6 10 16 26 42 68 110 178 288 466 7 11 18 29 47 76 123 199 322 521 843 9 14 23 37 60 97 157 254 411 665 1076 12 19 31 50 81 131 212 343 555 898 1453 15 24 39 63 102 165 267 432 699 1131 1830 17 27 44 71 115 186 301 487 788 1275 2063 20 32 52 84 136 220 356 576 932 1508 2440 22 35 57 92 149 241 390 631 1021 1652 2673 25 40 65 105 170 275 445 720 1165 1885 3050 28 45 73 118 191 309 500 809 1309 2118 3427
References
- Clark Kimberling, "Stolarsky Interspersions," Ars Combinatoria 39 (1995) 129-138. See page 135 for the dual Wythoff array and other dual arrays. - Clark Kimberling, Oct 29 2009
Links
- P. Hegarty, U. Larsson, Permutations of the natural numbers with prescribed difference multisets, Electr. J. Combin. Numb. Theory 6 (2006) #A03.
Crossrefs
First three rows identical to A035506. First column is A007066. First row is A000045. 2nd row is essentially A006355. 3rd row is essentially A000032. 4th row essentially A000285. 5th row essentially A013655 or A001060. 6th row essentially A022086 or A097135. 7th row essentially A022120. 8th row essentially A022087. 9th row essentially A022130. 10th row essentially A022088. 11th row essentially A022095. 12th row essentially A022089 etc.
Cf. A035513 (Wythoff array).
Programs
-
Maple
Tn1 := proc(T,nmax,row) local n,r,c,fnd; n := 1; while true do fnd := false; for r from 1 to row do for c from 1 to nmax do if T[r,c] = n then fnd := true; fi; od; if T[r,nmax] < n then RETURN(-1); fi; od; if fnd then n := n+1; else RETURN(n); fi; od; end; Tn2 := proc(T,nmax,row,ai1) local n,r,c,fnd; for r from 1 to row do for c from 1 to nmax do if T[r,c]+1 = ai1 then RETURN(T[r,c+1]+1); fi; od; od; RETURN(-1); end; T := proc(nmax) local a,col,row; a := array(1..nmax,1..nmax); for col from 1 to nmax do a[1,col] := combinat[fibonacci](col+1); od; for row from 2 to nmax do a[row,1] := Tn1(a,nmax,row-1); a[row,2] := Tn2(a,nmax,row-1,a[row,1]); for col from 3 to nmax do a[row,col] := a[row,col-2]+a[row,col-1]; od; od; RETURN(a); end; nmax := 12; a := T(nmax); for d from 1 to nmax do for row from 1 to d do printf("%d, ",a[row,d-row+1]); od; od;
-
Mathematica
(* program generates the dispersion array T of the complement of increasing sequence f[n] *) r = 40; r1 = 12; (* r=# rows of T, r1=# rows to show *) c = 40; c1 = 12; (* c=# cols of T, c1=# cols to show *) x = GoldenRatio; f[n_] := Floor[n*x + 2] (* f(n) is complement of column 1 *) mex[list_] := NestWhile[#1 + 1 &, 1, Union[list][[#1]] <= #1 &, 1, Length[Union[list]]] rows = {NestList[f, 1, c]}; Do[rows = Append[rows, NestList[f, mex[Flatten[rows]], r]], {r}]; t[i_, j_] := rows[[i, j]]; (* the array T *) TableForm[Table[t[i, j], {i, 1, 10}, {j, 1,10}]] (* Dual Wythoff array, A126714 *) Flatten[Table[t[k, n - k + 1], {n, 1, c1}, {k, 1, n}]] (* array as a sequence *) (* Program by Peter J. C. Moses, Jun 01 2011; added here by Clark Kimberling, Jun 03 2011 *)
A192750 Define a pair of sequences c_n, d_n by c_0=0, d_0=1 and thereafter c_n = c_{n-1}+d_{n-1}, d_n = c_{n-1}+4*n+2; sequence here is d_n.
1, 6, 11, 21, 36, 61, 101, 166, 271, 441, 716, 1161, 1881, 3046, 4931, 7981, 12916, 20901, 33821, 54726, 88551, 143281, 231836, 375121, 606961, 982086, 1589051, 2571141, 4160196, 6731341, 10891541, 17622886, 28514431, 46137321, 74651756
Offset: 0
Keywords
Comments
Links
- Harvey P. Dale, Table of n, a(n) for n = 0..1000
- Feng-Zhen Zhao, The log-behavior of some sequences related to the generalized Leonardo numbers, Integers (2024) Vol. 24, Art. No. A82.
- Index entries for linear recurrences with constant coefficients, signature (2, 0, -1).
Programs
-
Mathematica
q = x^2; s = x + 1; z = 40; p[0, n_] := 1; p[n_, x_] := x*p[n - 1, x] + 4 n + 2; Table[Expand[p[n, x]], {n, 0, 7}] reduce[{p1_, q_, s_, x_}] := FixedPoint[(s PolynomialQuotient @@ #1 + PolynomialRemainder @@ #1 &)[{#1, q, x}] &, p1] t = Table[reduce[{p[n, x], q, s, x}], {n, 0, z}]; u1 = Table[Coefficient[Part[t, n], x, 0], {n, 1, z}] (* A192750 *) u2 = Table[Coefficient[Part[t, n], x, 1], {n, 1, z}] (* A192751 *) LinearRecurrence[{2,0,-1},{1,6,11},40] (* Harvey P. Dale, Dec 03 2023 *)
Formula
G.f.: ( 1+4*x-x^2 ) / ( (x-1)*(x^2+x-1) ). The first differences are in A022088. - R. J. Mathar, May 04 2014
a(n) = 5*Fibonacci(n+2)-4. - Gerry Martens, Jul 04 2015
Extensions
Entry revised by N. J. A. Sloane, Dec 15 2015
A192751 Define a pair of sequences c_n, d_n by c_0=0, d_0=1 and thereafter c_n = c_{n-1}+d_{n-1}, d_n = c_{n-1}+4*n+2; sequence here is c_n.
0, 1, 7, 18, 39, 75, 136, 237, 403, 674, 1115, 1831, 2992, 4873, 7919, 12850, 20831, 33747, 54648, 88469, 143195, 231746, 375027, 606863, 981984, 1588945, 2571031, 4160082, 6731223, 10891419, 17622760, 28514301, 46137187, 74651618, 120788939
Offset: 0
Keywords
Comments
Links
- Harvey P. Dale, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (3,-2,-1,1).
Programs
-
Mathematica
(See A192750.) CoefficientList[Series[x (x^2-4x-1)/((x-1)^2(x^2+x-1)),{x,0,40}],x] (* or *) LinearRecurrence[{3,-2,-1,1},{0,1,7,18},40] (* Harvey P. Dale, Feb 23 2022 *)
Formula
G.f.: x*(x^2-4*x-1)/((x-1)^2*(x^2+x-1)). First differences are in A192750. [Colin Barker, Nov 13 2012]
a(n) = 5*Fibonacci(n+3) - (4*n+10). - N. J. A. Sloane, Dec 15 2015
Extensions
Description corrected by Antti Karttunen, Dec 15 2015
Entry revised by N. J. A. Sloane, Dec 15 2015
A229339 GCD of all sums of n consecutive Lucas numbers.
1, 1, 2, 5, 1, 4, 1, 15, 2, 11, 1, 40, 1, 29, 2, 105, 1, 76, 1, 275, 2, 199, 1, 720, 1, 521, 2, 1885, 1, 1364, 1, 4935, 2, 3571, 1, 12920, 1, 9349, 2, 33825, 1, 24476, 1, 88555, 2, 64079, 1, 231840, 1, 167761, 2, 606965, 1, 439204, 1, 1589055, 2, 1149851, 1, 4160200, 1, 3010349, 2
Offset: 1
Comments
The sum of two consecutive Lucas number is the sum of four consecutive Fibonacci numbers, which is verified easily enough with the identity L(n) = F(n - 1) + F(n + 1). Therefore a(1) = a(2) = A210209(4).
Examples
a(3) = 2 because any sum of three consecutive Lucas numbers is an even number. a(4) = 5 because all sums of four consecutive Lucas numbers are divisible by 5. a(5) = 1 because some sums of five consecutive Lucas numbers are coprime.
Links
- Colin Barker, Table of n, a(n) for n = 1..1000
- Dan Guyer and aBa Mbirika, GCD of sums of k consecutive Fibonacci, Lucas, and generalized Fibonacci numbers, Journal of Integer Sequences, 24 No.9, Article 21.9.8 (2021), 25pp; arXiv preprint, arXiv:2104.12262 [math.NT], 2021.
- Index entries for linear recurrences with constant coefficients, signature (0,0,0,3,0,1,0,-1,0,-3,0,0,0,1).
Programs
-
Mathematica
a[n_] := a[n] = If[n <= 14, {1, 1, 2, 5, 1, 4, 1, 15, 2, 11, 1, 40, 1, 29}[[n]], 3*a[n - 4] + a[n - 6] - a[n - 8] - 3*a[n - 10] + a[n - 14]]; Array[a, 64] (* Giovanni Resta, Oct 04 2013 *) CoefficientList[Series[(x^12 - x^11 + 2 x^10 - 5 x^9 - 2 x^8 - x^7 - 6 x^6 + x^5 - 2 x^4 + 5 x^3 + 2 x^2 + x + 1) / (-x^14 + 3 x^10 + x^8 - x^6 - 3 x^4 + 1), {x, 0, 40}], x] (* Vincenzo Librandi, Nov 09 2014 *) LinearRecurrence[{0,0,0,3,0,1,0,-1,0,-3,0,0,0,1},{1,1,2,5,1,4,1,15,2,11,1,40,1,29},70] (* Harvey P. Dale, Jul 21 2021 *) Table[GCD[LucasL[n + 1] - 2, LucasL[n] + 1], {n, 0, 50}] (* Horst H. Manninger, Dec 25 2021 *)
-
PARI
Vec(x*(x^12 -x^11 +2*x^10 -5*x^9 -2*x^8 -x^7 -6*x^6 +x^5 -2*x^4 +5*x^3 +2*x^2 +x +1) / (-x^14 +3*x^10 +x^8 -x^6 -3*x^4 +1) + O(x^100)) \\ Colin Barker, Nov 09 2014
Formula
a(n) = 3*a(n-4) + a(n-6) - a(n-8) - 3*a(n-10) + a(n-14) for n > 14. - Giovanni Resta, Oct 04 2013
G.f.: x*(x^12 -x^11 +2*x^10 -5*x^9 -2*x^8 -x^7 -6*x^6 +x^5 -2*x^4 +5*x^3 +2*x^2 +x +1) / (-x^14 +3*x^10 +x^8 -x^6 -3*x^4 +1). - Colin Barker, Nov 09 2014
From Aba Mbirika, Jan 04 2022: (Start)
a(n) = gcd(L(n+1)-1, L(n+2)-3).
a(n) = Lcm_{A106291(m) divides n} m.
Proofs of these formulas are given in Theorems 15 and 25 of the Guyer-Mbirika paper. (End)
A354265 Array read by ascending antidiagonals for n >= 0 and k >= 0. Generalized Lucas numbers, L(n, k) = (psi^(k - 1)*(phi + n) - phi^(k - 1)*(psi + n)), where phi = (1 + sqrt(5))/2 and psi = (1 - sqrt(5))/2.
2, 3, 1, 4, 4, 3, 5, 7, 7, 4, 6, 10, 11, 11, 7, 7, 13, 15, 18, 18, 11, 8, 16, 19, 25, 29, 29, 18, 9, 19, 23, 32, 40, 47, 47, 29, 10, 22, 27, 39, 51, 65, 76, 76, 47, 11, 25, 31, 46, 62, 83, 105, 123, 123, 76, 12, 28, 35, 53, 73, 101, 134, 170, 199, 199, 123
Offset: 0
Comments
The definition declares the Lucas numbers for all integers n and k. It gives the classical Lucas numbers as L(0, n) = Lucas(n), where Lucas(n) = A000032(n) is extended in the usual way for negative n.
Examples
Array starts: [0] 2, 1, 3, 4, 7, 11, 18, 29, 47, 76, ... A000032 [1] 3, 4, 7, 11, 18, 29, 47, 76, 123, 199, ... A000032 (shifted) [2] 4, 7, 11, 18, 29, 47, 76, 123, 199, 322, ... A000032 (shifted) [3] 5, 10, 15, 25, 40, 65, 105, 170, 275, 445, ... A022088 [4] 6, 13, 19, 32, 51, 83, 134, 217, 351, 568, ... A022388 [5] 7, 16, 23, 39, 62, 101, 163, 264, 427, 691, ... A190995 [6] 8, 19, 27, 46, 73, 119, 192, 311, 503, 814, ... A206420 [7] 9, 22, 31, 53, 84, 137, 221, 358, 579, 937, ... A206609 [8] 10, 25, 35, 60, 95, 155, 250, 405, 655, 1060, ... [9] 11, 28, 39, 67, 106, 173, 279, 452, 731, 1183, ...
Links
- Peter Luschny, The Fibonacci Function.
Programs
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Julia
const FibMem = Dict{Int,Tuple{BigInt,BigInt}}() function FibRec(n::Int) get!(FibMem, n) do n == 0 && return (BigInt(0), BigInt(1)) a, b = FibRec(div(n, 2)) c = a * (b * 2 - a) d = a * a + b * b iseven(n) ? (c, d) : (d, c + d) end end function Lucas(n, k) k == 0 && return BigInt(n + 2) k == -1 && return BigInt(2 * n - 1) k < 0 && return (-1)^k * Lucas(1 - n, -k - 2) a, b = FibRec(k) c, d = FibRec(k - 1) n * (2 * a + b) + 2 * c + d end for n in -6:6 println([Lucas(n, k) for k in -6:6]) end
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Maple
phi := (1 + sqrt(5))/2: psi := (1 - sqrt(5))/2: L := (n, k) -> phi^(k+1)*(n - psi) + psi^(k+1)*(n - phi): seq(seq(simplify(L(n-k, k)), k = 0..n), n = 0..10);
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Mathematica
L[n_, k_] := With[{c = Pi/2 + I*ArcCsch[2]}, I^k Sec[c] (n Cos[c (k + 1)] - I Cos[c k]) ]; Table[Simplify[L[n, k]], {n, 0, 6}, {k, 0, 6}] // TableForm (* Alternative: *) L[n_, k_] := n*LucasL[k + 1] + LucasL[k]; Table[Simplify[L[n, k]], {n, 0, 6}, {k, 0, 6}] // TableForm
Formula
Functional equation extends Cassini's theorem:
L(n, k) = (-1)^k*L(1 - n, -k - 2).
L(n, k) = n*Lucas(k + 1) + Lucas(k).
L(n, k) = L(n, k-1) + L(n, k-2).
L(n, k) = i^k*sec(c)*(n*cos(c*(k + 1)) - i*cos(c*k)), where c = Pi/2 + i*arccsch(2), for all n, k in Z.
Using the generalized Fibonacci numbers F(n, k) = A352744(n, k),
L(n, k) = F(n, k+1) + F(n, k) + F(n, k-1) + F(n, k-2).
Comments
Examples
References
Links
Crossrefs
Programs
Maple
Mathematica
PARI
Python
Python
Formula
Extensions