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
A258160 a(n) = 8*Lucas(n).
16, 8, 24, 32, 56, 88, 144, 232, 376, 608, 984, 1592, 2576, 4168, 6744, 10912, 17656, 28568, 46224, 74792, 121016, 195808, 316824, 512632, 829456, 1342088, 2171544, 3513632, 5685176, 9198808, 14883984, 24082792, 38966776, 63049568, 102016344, 165065912
Offset: 0
Links
- Bruno Berselli, Table of n, a(n) for n = 0..300
- Tanya Khovanova, Recursive Sequences: a(n) = a(n-1)+a(n-2).
- Index entries for linear recurrences with constant coefficients, signature (1,1).
Crossrefs
Programs
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Magma
[8*Lucas(n): n in [0..40]];
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Mathematica
Table[8 LucasL[n], {n, 0, 40}] CoefficientList[Series[8*(2 - x)/(1 - x - x^2), {x, 0, 50}], x] (* G. C. Greubel, Dec 21 2017 *)
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PARI
a(n)=([0,1; 1,1]^n*[16;8])[1,1] \\ Charles R Greathouse IV, Oct 07 2015
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Sage
[8*lucas_number2(n, 1, -1) for n in (0..40)]
Formula
G.f.: 8*(2 - x)/(1 - x - x^2).
a(n) = Fibonacci(n+6) - Fibonacci(n-6), where Fibonacci(-6..-1) = -8, 5, -3, 2, -1, 1 (see similar sequences listed in Crossrefs).
a(n) = Lucas(n+4) + Lucas(n) + Lucas(n-4), where Lucas(-4..-1) = 7, -4, 3, -1.
a(n) = a(n-1) + a(n-2) for n>1, a(0)=16, a(1)=8.
a(n) = 2*A156279(n).
a(n+1) = 4*A022112(n).
A210209 GCD of all sums of n consecutive Fibonacci numbers.
0, 1, 1, 2, 1, 1, 4, 1, 3, 2, 11, 1, 8, 1, 29, 2, 21, 1, 76, 1, 55, 2, 199, 1, 144, 1, 521, 2, 377, 1, 1364, 1, 987, 2, 3571, 1, 2584, 1, 9349, 2, 6765, 1, 24476, 1, 17711, 2, 64079, 1, 46368, 1, 167761, 2, 121393, 1, 439204, 1, 317811, 2, 1149851, 1, 832040
Offset: 0
Comments
Early on in the Posamentier & Lehmann (2007) book, the fact that the sum of any ten consecutive Fibonacci numbers is a multiple of 11 is presented as an interesting property of the Fibonacci numbers. Much later in the book a proof of this fact is given, using arithmetic modulo 11. An alternative proof could demonstrate that 11*F(n + 6) = Sum_{i=n..n+9} F(i).
Examples
a(3) = 2 because all sums of three consecutive Fibonacci numbers are divisible by 2 (F(n) + F(n-1) + F(n-2) = 2F(n)), but since the GCD of 3 + 5 + 8 = 16 and 5 + 8 + 13 = 26 is 2, no number larger than 2 divides all sums of three consecutive Fibonacci numbers. a(4) = 1 because the GCD of 1 + 1 + 2 + 3 = 7 and 1 + 2 + 3 + 5 = 11 is 1, so the sums of four consecutive Fibonacci numbers have no factors in common.
References
- Alfred S. Posamentier & Ingmar Lehmann, The (Fabulous) Fibonacci Numbers, Prometheus Books, New York (2007) p. 33.
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..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.
- I. D. Ruggles, Elementary problem B-1, Fibonacci Quarterly, Vol. 1, No. 1, February 1963, p. 73; Solution by Marjorie R. Bicknell, published in Vol. 1, No. 3, October 1963, pp. 76-77.
- Index entries for linear recurrences with constant coefficients, signature (0,0,0,3,0,1,0,-1,0,-3,0,0,0,1).
Crossrefs
Programs
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Maple
a:= n-> (Matrix(7, (i, j)-> `if`(i=j-1, 1, `if`(i=7, [1, 0, -3, -1, 1, 3, 0][j], 0)))^iquo(n, 2, 'r'). `if`(r=0, <<0, 1, 1, 4, 3, 11, 8>>, <<1, 2, 1, 1, 2, 1, 1>>))[1, 1]: seq(a(n), n=0..80); # Alois P. Heinz, Mar 18 2012
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Mathematica
Table[GCD[Fibonacci[n + 1] - 1, Fibonacci[n]], {n, 1, 50}] (* Horst H. Manninger, Dec 19 2021 *)
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PARI
a(n)=([0,1,0,0,0,0,0,0,0,0,0,0,0,0; 0,0,1,0,0,0,0,0,0,0,0,0,0,0; 0,0,0,1,0,0,0,0,0,0,0,0,0,0; 0,0,0,0,1,0,0,0,0,0,0,0,0,0; 0,0,0,0,0,1,0,0,0,0,0,0,0,0; 0,0,0,0,0,0,1,0,0,0,0,0,0,0; 0,0,0,0,0,0,0,1,0,0,0,0,0,0; 0,0,0,0,0,0,0,0,1,0,0,0,0,0; 0,0,0,0,0,0,0,0,0,1,0,0,0,0; 0,0,0,0,0,0,0,0,0,0,1,0,0,0; 0,0,0,0,0,0,0,0,0,0,0,1,0,0; 0,0,0,0,0,0,0,0,0,0,0,0,1,0; 0,0,0,0,0,0,0,0,0,0,0,0,0,1; 1,0,0,0,-3,0,-1,0,1,0,3,0,0,0]^n*[0;1;1;2;1;1;4;1;3;2;11;1;8;1])[1,1] \\ Charles R Greathouse IV, Jun 20 2017
Formula
G.f.: -x*(x^12-x^11+2*x^10-x^9-2*x^8-x^7-6*x^6+x^5-2*x^4+x^3+2*x^2+x+1) / (x^14-3*x^10-x^8+x^6+3*x^4-1) = -1/(x^4+x^2-1) + (x^2+1)/(x^4-x^2-1) + (x+2)/(6*(x^2+x+1)) + (x-2)/(6*(x^2-x+1)) - 2/(3*(x+1)) - 2/(3*(x-1)). - Alois P. Heinz, Mar 18 2012
a(n) = gcd(Fibonacci(n+1)-1, Fibonacci(n)). - Horst H. Manninger, Dec 19 2021
From Aba Mbirika, Jan 21 2022: (Start)
a(n) = gcd(F(n+1)-1, F(n+2)-1).
a(n) = Lcm_{A001175(m) divides n} m.
Proofs of these formulas are given in Theorems 15 and 25 of the Guyer-Mbirika paper. (End)
Extensions
More terms from Alois P. Heinz, Mar 18 2012
A230448 T(n, k) = T(n-1, k-1) + T(n-1, k) with T(n, 0) = 1 and T(n, n) = A226205(n+1), n >= 0 and 0 <= k <= n.
1, 1, 0, 1, 1, 3, 1, 2, 4, 5, 1, 3, 6, 9, 16, 1, 4, 9, 15, 25, 39, 1, 5, 13, 24, 40, 64, 105, 1, 6, 18, 37, 64, 104, 169, 272, 1, 7, 24, 55, 101, 168, 273, 441, 715, 1, 8, 31, 79, 156, 269, 441, 714, 1156, 1869, 1, 9, 39, 110, 235, 425, 710, 1155, 1870, 3025, 4896
Offset: 0
Comments
Examples
The first few rows of triangle T(n, k), n >= 0 and 0 <= k <= n. n/k 0 1 2 3 4 5 6 7 ------------------------------------------------ 0| 1 1| 1, 0 2| 1, 1, 3 3| 1, 2, 4, 5 4| 1, 3, 6, 9, 16 5| 1, 4, 9, 15, 25, 39 6| 1, 5, 13, 24, 40, 64, 105 7| 1, 6, 18, 37, 64, 104, 169, 272 The triangle as a square array Tsq(n, k) = T(n+k, k), n >= 0 and k >= 0. n/k 0 1 2 3 4 5 6 7 ------------------------------------------------ 0| 1, 0, 3, 5, 16, 39, 105, 272 1| 1, 1, 4, 9, 25, 64, 169, 441 2| 1, 2, 6, 15, 40, 104, 273, 714 3| 1, 3, 9, 24, 64, 168, 441, 1155 4| 1, 4, 13, 37, 101, 269, 710, 1865 5| 1, 5, 18, 55, 156, 425, 1135, 3000 6| 1, 6, 24, 79, 235, 660, 1795, 4795 7| 1, 7, 31, 110, 345, 1005, 2800, 7595
Crossrefs
Programs
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Maple
T := proc(n, k) option remember: if k=0 then return(1) elif k=n then return(combinat[fibonacci](n+2)*combinat[fibonacci](n-1)) else procname(n-1, k-1) + procname(n-1, k) fi: end: seq(seq(T(n, k), k=0..n), n=0..10); # End first program. T := proc(n, k): add(A035317(n+k-p-2, p), p=0..k) end: A035317 := proc(n, k): add((-1)^(i+k) * binomial(i+n-k+1, i), i=0..k) end: seq(seq(T(n, k), k=0..n), n=0..10); # End second program.
Formula
T(n, k) = T(n-1, k-1) + T(n-1, k) with T(n, 0) = 1 and T(n, n) = F(n+2) * F(n-1) = A226205(n+1) with F(n) = A000045(n), the Fibonacci numbers, n >= 0 and 0 <= k <= n.
T(n, k) = sum(A035317(n+k-p-2, p), p=0..k), n >= 0 and 0 <= k <= n.
T(n+p+2, p-2) = A080239(n+2*p-1) - sum(A035317(n-k+p-1, k+p-1), k=0..floor(n/2)), n >= 0 and p >= 2.
The triangle as a square array Tsq(n, k) = T(n+k, k), n >= 0 and k >= 0.
Tsq(n, k) = sum(Tsq(n-1, i), i=0..k), n >= 1 and k >= 0, with Tsq(0, k) = A226205(k+1).
The two G.f.’s given below generate the terms in the n-th row of the square array Tsq(n, k). The remarkable second G.f. is the partial fraction expansion of the first G.f..
G.f.: 1/((1-x)^(n-2)*(1+x)*(x^2-3*x+1)), n >= 0.
A282465 a(n) = 11*Fibonacci(n+3) + Fibonacci(n-8) with n>=0.
1, 46, 47, 93, 140, 233, 373, 606, 979, 1585, 2564, 4149, 6713, 10862, 17575, 28437, 46012, 74449, 120461, 194910, 315371, 510281, 825652, 1335933, 2161585, 3497518, 5659103, 9156621, 14815724, 23972345, 38788069, 62760414, 101548483, 164308897, 265857380, 430166277
Offset: 0
Comments
Similar sequences with the formula h*Fibonacci(n+k) + Fibonacci(n+k-h):
h= 1, k=-1: A000045;
h= 2, k= 1: A013655;
h= 5, k= 1: A022113;
h= 6, k= 2: A022125;
h= 7, k= 3: A097657;
h= 9, k= 3: 10, 32, 42, 74, 116, 190, 306, 496, 802, ... = 2*A022140;
h=10, k= 3: 33, 22, 55, 77, 132, 209, 341, 550, 891, ... = 11*A013655;
h=11, k= 3: this sequence.
Links
- Indranil Ghosh, Table of n, a(n) for n = 0..4769
- Tanya Khovanova, Recursive Sequences
- Index entries for linear recurrences with constant coefficients, signature (1,1).
Crossrefs
Programs
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Magma
[11*Fibonacci(n+3)+Fibonacci(n-8): n in [0..40]];
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Mathematica
Table[11 Fibonacci[n + 3] + Fibonacci[n - 8], {n, 0, 40}] LinearRecurrence[{1,1},{1,46},36] (* or *) CoefficientList[Series[(1 + 45*x)/(1 - x - x^2) , {x,0,35}],x] (* Indranil Ghosh, Feb 22 2017 *)
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PARI
a(n) = 11*fibonacci(n+3) + fibonacci(n-8) \\ Indranil Ghosh, Feb 23 2017
Formula
G.f.: (1 + 45*x)/(1 - x - x^2).
a(n) = a(n-1) + a(n-2).
a(n) = a(i)*Fibonacci(n-i+1) + a(i-1)*Fibonacci(n-i). Examples:
for i= 3, a(3)=93, a(2)= 47: a(n) = 93*Fibonacci(n-2) + 47*Fibonacci(n-3);
for i=-1, a(-1)=45, a(-2)=-44: a(n) = 45*Fibonacci(n+2) - 44*Fibonacci(n+1).
Other formulae:
a(n) = 44*Fibonacci(n) + Fibonacci(n+2),
a(n) = 45*Fibonacci(n) + Fibonacci(n+1),
a(n) = 46*Fibonacci(n) + Fibonacci(n-1),
a(n) = 47*Fibonacci(n) - Fibonacci(n-2).
a(n) = ((91 + sqrt(5))*((1 + sqrt(5))/2)^n - (91 - sqrt(5))*((1 - sqrt(5))/2)^n)/sqrt(20).
A347351 Triangle read by rows: T(n,k) is the number of links of length k in a set of all necklaces A000358 of length n, 1 <= k <= n.
1, 2, 1, 3, 0, 1, 4, 2, 0, 1, 5, 1, 1, 0, 1, 6, 4, 2, 1, 0, 1, 7, 3, 2, 1, 1, 0, 1, 8, 8, 3, 3, 1, 1, 0, 1, 9, 8, 7, 3, 2, 1, 1, 0, 1, 10, 18, 9, 5, 4, 2, 1, 1, 0, 1, 11, 21, 13, 8, 5, 3, 2, 1, 1, 0, 1, 12, 40, 24, 16, 8, 6, 3, 2, 1, 1, 0, 1, 13, 55, 34, 21, 13, 8, 5, 3, 2, 1, 1, 0, 1
Offset: 0
Comments
Definitions:
1. A link is any 0 in any necklace from A000358 and all 1s following this 0 in this necklace to right until another 0 is encountered.
2. Length of the link is the number of elements in the link.
Sum of all elements n-row is Fibonacci(n-1)+n iff n=1 or n=p (follows from the identity for the sum of the Fibonacci numbers and the formula for the triangle T(n,k)).
Examples
For k > 0: n\k | 1 2 3 4 5 6 7 8 9 10 ... -----+--------------------------------------- 1 | 1 2 | 2 1 3 | 3 0 1 4 | 4 2 0 1 5 | 5 1 1 0 1 6 | 6 4 2 1 0 1 7 | 7 3 2 1 1 0 1 8 | 8 8 3 3 1 1 0 1 9 | 9 8 7 3 2 1 1 0 1 10 | 10 18 9 5 4 2 1 1 0 1 ... If we continue the calculation for nonpositive k, we get a table in which each row is a Fibonacci sequence, in which term(0) = A113166, term(1) = A034748. For k <= 0: n\k | 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 ... -----+------------------------------------------------ 1 | 0 1 1 2 3 5 8 13 21 34 ... A000045 2 | 1 2 3 5 8 13 21 34 55 89 ... A000045 3 | 1 4 5 9 14 23 37 60 97 157 ... A000285 4 | 3 6 9 15 24 39 63 102 165 267 ... A022086 5 | 3 9 12 21 33 54 87 141 228 369 ... A022379 6 | 8 14 22 36 58 94 152 246 398 644 ... A022112 7 | 8 19 27 46 73 119 192 311 503 814 ... A206420 8 | 17 30 47 77 124 201 325 526 851 1377 ... A022132 9 | 23 44 67 111 178 289 467 756 1223 1979 ... A294116 10 | 41 68 109 177 286 463 749 1212 1961 3173 ... A022103 ...
Programs
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MATLAB
function [res] = calcLinks(n,k) if k==1 res=n; else d=divisors(n); res=0; for i=1:length(d) if d (i) >= k res=res+eulerPhi(n/d(i))*fiboExt(d(i)-k-1); end end end function [s] = fiboExt(m) % extended fibonacci function (including negative arguments) m=sym(m); % for large fibonacci numbers if m>=0 || mod(m,2)==1 s=fibonacci(abs(m)); else s=fibonacci(abs(m))*(-1); end
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PARI
T(n, k) = if (k==1, n, sumdiv(n, d, if (d>=k, eulerphi(n/d)*fibonacci(d-k-1)))); \\ Michel Marcus, Aug 29 2021
Formula
If k=1, T(n,k)=n, otherwise T(n,k) = Sum_{d>=k, d|n} Phi(n/d)*Fibonacci(d-k-1), where Phi=A000010.
Comments
Examples
References
Links
Crossrefs
Programs
Maple
Mathematica
PARI
Python
Python
Formula
Extensions