cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A180673 a(n) = Fibonacci(n+8) - Fibonacci(8).

Original entry on oeis.org

0, 13, 34, 68, 123, 212, 356, 589, 966, 1576, 2563, 4160, 6744, 10925, 17690, 28636, 46347, 75004, 121372, 196397, 317790, 514208, 832019, 1346248, 2178288, 3524557, 5702866, 9227444, 14930331, 24157796, 39088148, 63245965, 102334134
Offset: 0

Views

Author

Johannes W. Meijer, Sep 21 2010

Keywords

Comments

The a(n+1) (terms doubled) are the Kn17 sums of the Fibonacci(n) triangle A104763. See A180662 for information about these knight and other chess sums.

Crossrefs

Cf. A131524 (Kn11), A001911 (Kn12), A006327 (Kn13), A167616 (Kn14), A180671 (Kn15), A180672 (Kn16), A180673 (Kn17), A180674 (Kn18).

Programs

  • GAP
    List([0..40], n-> Fibonacci(n+8)-21); # G. C. Greubel, Jul 13 2019
  • Magma
    [Fibonacci(n+8) - Fibonacci(8): n in [0..40]]; // Vincenzo Librandi, Apr 24 2011
    
  • Maple
    nmax:=40: with(combinat): for n from 0 to nmax do a(n):=fibonacci(n+8)-fibonacci(8) od: seq(a(n),n=0..nmax);
  • Mathematica
    Fibonacci[8 +Range[0, 40]] -21 (* G. C. Greubel, Jul 13 2019 *)
  • PARI
    concat(0, Vec(x*(13+8*x)/((1-x)*(1-x-x^2)) + O(x^40))) \\ Colin Barker, Feb 24 2017
    
  • PARI
    a(n)=fibonacci(n+8)-21 \\ Charles R Greathouse IV, Feb 24 2017
    
  • SageMath
    [fibonacci(n+8)-21 for n in (0..40)] # G. C. Greubel, Jul 13 2019
    

Formula

a(n) = F(n+8) - F(8) with F(n) the Fibonacci numbers A000045.
a(n) = a(n-1) + a(n-2) + 21 for n>1, a(0)=0, a(1)=13, and where 21 = F(8).
G.f.: x*(13 + 8*x)/((1 - x)*(1 - x - x^2)). - Ilya Gutkovskiy, Feb 24 2017
a(n) = 13*A000071(n+2) + 8*A000071(n+1). - Bruno Berselli, Feb 24 2017
From Colin Barker, Feb 24 2017: (Start)
a(n) = (-21 + (2^(-1-n)*((1-sqrt(5))^n*(-47+21*sqrt(5)) + (1+sqrt(5))^n*(47+21*sqrt(5)))) / sqrt(5)).
a(n) = 2*a(n-1) - a(n-3) for n>2. (End)

A180674 a(n) = Fibonacci(n+9) - Fibonacci(9).

Original entry on oeis.org

0, 21, 55, 110, 199, 343, 576, 953, 1563, 2550, 4147, 6731, 10912, 17677, 28623, 46334, 74991, 121359, 196384, 317777, 514195, 832006, 1346235, 2178275, 3524544, 5702853, 9227431, 14930318, 24157783, 39088135, 63245952, 102334121
Offset: 0

Views

Author

Johannes W. Meijer, Sep 21 2010

Keywords

Comments

The a(n+1) (terms doubled) are the Kn18 sums of the Fibonacci(n) triangle A104763. See A180662 for information about these knight and other chess sums.

Crossrefs

Cf. A131524 (Kn11), A001911 (Kn12), A006327 (Kn13), A167616 (Kn14), A180671 (Kn15), A180672 (Kn16), A180673 (Kn17), A180674 (Kn18).

Programs

  • GAP
    List([0..40], n-> Fibonacci(n+9)-34); # G. C. Greubel, Jul 13 2019
  • Magma
    [Fibonacci(n+9) - Fibonacci(9): n in [0..40]]; // Vincenzo Librandi, Apr 24 2011
    
  • Maple
    nmax:=31: with(combinat): for n from 0 to nmax do a(n):=fibonacci(n+9)-fibonacci(9) od: seq(a(n),n=0..nmax);
  • Mathematica
    Fibonacci[9 +Range[0, 40]] -34 (* G. C. Greubel, Jul 13 2019 *)
    LinearRecurrence[{2,0,-1},{0,21,55},40] (* Harvey P. Dale, Aug 24 2024 *)
  • PARI
    concat(0, Vec(x*(21+13*x)/((1-x)*(1-x-x^2)) + O(x^40))) \\ Colin Barker, Feb 24 2017
    
  • PARI
    a(n) = fibonacci(n+9) - fibonacci(9) \\ Charles R Greathouse IV, Feb 24 2017
    
  • Sage
    [fibonacci(n+9)-34 for n in (0..40)] # G. C. Greubel, Jul 13 2019
    

Formula

a(n) = F(n+9) - F(9) with F = A000045.
a(n) = a(n-1) + a(n-2) + 34 for n>1, a(0)=0, a(1)=21, and where 34 = F(9).
G.f.: x*(21 + 13*x)/((1 - x)*(1 - x - x^2)). - Ilya Gutkovskiy, Feb 24 2017
a(n) = 21*A000071(n+2) + 13*A000071(n+1). - Bruno Berselli, Feb 24 2017
From Colin Barker, Feb 24 2017: (Start)
a(n) = (-34 + (2^(-n)*((1-sqrt(5))^n*(-38+17*sqrt(5)) + (1+sqrt(5))^n*(38+17*sqrt(5)))) / sqrt(5)).
a(n) = 2*a(n-1) - a(n-3) for n>2. (End)

A232580 Number of binary sequences of length n that contain at least one contiguous subsequence 011.

Original entry on oeis.org

0, 0, 0, 1, 4, 12, 31, 74, 168, 369, 792, 1672, 3487, 7206, 14788, 30185, 61356, 124308, 251199, 506578, 1019920, 2050785, 4119280, 8267216, 16580799, 33236622, 66594636, 133385689, 267089188, 534692604, 1070217247, 2141780762, 4285739832, 8575004241
Offset: 0

Views

Author

Geoffrey Critzer, Nov 26 2013

Keywords

Comments

From Gus Wiseman, Jun 26 2022: (Start)
Also the number of integer compositions of n + 1 with an even part other than the first or last. For example, the a(3) = 1 through a(5) = 12 compositions are:
(121) (122) (123)
(221) (141)
(1121) (222)
(1211) (321)
(1122)
(1212)
(1221)
(2121)
(2211)
(11121)
(11211)
(12111)
The odd version is A274230.
(End)

Examples

			a(4) = 4 because we have: 0011, 0110, 0111, 1011.
		

Crossrefs

The complement is counted by A000071(n) = A001911(n) + 1.
For the contiguous pattern (1,1) or (0,0) we have A000225.
For the contiguous pattern (1,0,1) or (0,1,0) we have A000253.
For the contiguous pattern (1,0) or (0,1) we have A000295.
Numbers whose binary expansion is of this type are A004750.
For the contiguous pattern (1,1,1) or (0,0,0) we have A050231.
The not necessarily contiguous version is A324172.

Programs

  • Mathematica
    nn=40;a=x/(1-x);CoefficientList[Series[a^2 x/(1-a x)/(1-2x),{x,0,nn}],x]
    (* second program *)
    Table[Length[Select[Tuples[{0,1},n],MatchQ[#,{_,0,1,1,_}]&]],{n,0,10}] (* Gus Wiseman, Jun 26 2022 *)
  • PARI
    concat(vector(3), Vec(x^3/(-2*x^4+x^3+4*x^2-4*x+1) + O(x^40))) \\ Colin Barker, Nov 03 2016

Formula

O.g.f.: x^3/( (1-x)^2*(1-x^2/(1-x))*(1-2x) ).
a(n) ~ 2^n.
From Colin Barker, Nov 03 2016: (Start)
a(n) = (1 + 2^n - (2^(-n)*((1-sqrt(5))^n*(-2+sqrt(5)) + (1+sqrt(5))^n*(2+sqrt(5))))/sqrt(5)).
a(n) = 4*a(n-1) - 4*a(n-2) - a(n-3) + 2*a(n-4) for n > 3. (End)
a(n) = 2^n - Fibonacci(n+3) + 1. - Ehren Metcalfe, Dec 27 2018
E.g.f.: 2*exp(x/2)*(5*exp(x)*cosh(x/2) - 5*cosh(sqrt(5)*x/2) - 2*sqrt(5)*sinh(sqrt(5)*x/2))/5. - Stefano Spezia, Apr 06 2022

A104004 Expansion of (1-x) * (1+x) / ((1-2*x)*(1-x-x^2)).

Original entry on oeis.org

1, 3, 7, 16, 35, 75, 158, 329, 679, 1392, 2839, 5767, 11678, 23589, 47555, 95720, 192427, 386451, 775486, 1555153, 3117071, 6245088, 12507887, 25044431, 50135230, 100345485, 200812363, 401821144, 803960099, 1608434427, 3217700894, 6436748057
Offset: 0

Views

Author

Creighton Dement, Feb 24 2005

Keywords

Comments

A floretion-generated sequence relating to Fibonacci numbers and powers of 2. The sequence results from a particular transform of the sequence A000079*(-1)^n (powers of 2).
Floretion Algebra Multiplication Program, FAMP Code: 1jesforseq[ ( 5'i + .5i' + .5'ii' + .5e)*( + .5j' + .5'kk' + .5'ki' + .5e ) ], 1vesforseq = A000079(n+1)*(-1)^(n+1), ForType: 1A. Identity used: jesfor = jesrightfor + jesleftfor

Crossrefs

Programs

  • Magma
    [3*2^n-Fibonacci(n+3): n in [0..40]]; // Vincenzo Librandi, Aug 18 2017
    
  • Maple
    with (combinat):a[0]:=0:a[1]:=1:for n from 2 to 50 do a[n]:=fibonacci(n-1)+2*a[n-1] od: seq(a[n], n=1..26); # Zerinvary Lajos, Mar 17 2008
  • Mathematica
    LinearRecurrence[{3, -1, -2}, {1, 3, 7}, 80] (* Vincenzo Librandi, Aug 18 2017 *)
    CoefficientList[Series[(1-x)(1+x)/((2x-1)(x^2+x-1)),{x,0,40}],x] (* Harvey P. Dale, Oct 12 2024 *)
    A104004[n_]:= 3*2^n -Fibonacci[n+3]; (* G. C. Greubel, Jun 05 2025 *)
  • SageMath
    def A104004(n): return 3*2**n - fibonacci(n+3) # G. C. Greubel, Jun 05 2025

Formula

4*a(n) = A008466(n+3) + A027973(n) (FAMP result).
Suggestions made by Superseeker: (Start)
a(n+2) - a(n+1) - a(n) = A042950(n+1).
Coefficients of g.f.*(1-x)/(1+x) match A099036.
Coefficients of g.f./(1+x) match A027934.
Coefficients of g.f./(1-x^2) match A008466. (End)
a(n) = A101220(3, 2, n+1) - A101220(3, 2, n). - Ross La Haye, Aug 05 2005
a(n) = 3*2^n - Fibonacci(n+3) = A221719(n) + 1. - Ralf Stephan, May 20 2007, Hugo Pfoertner, Mar 06 2024
a(n) = (3*2^n - (2^(-n)*((1-sqrt(5))^n*(-2+sqrt(5)) + (1+sqrt(5))^n*(2+sqrt(5)))) / sqrt(5)). - Colin Barker, Aug 18 2017
From G. C. Greubel, Jun 05 2025: (Start)
Sum_{k=0..n} A022958(k+1)*a(n-k) = A001911(n+1).
Sum_{k=0..n} (-1)^k*A016777(k)*a(n-k) = A078024(n).
E.g.f.: 3*exp(2*x) - (2/sqrt(5))*exp(x/2)*( 2*sinh(sqrt(5)*x/2) + sqrt(5)*cosh(sqrt(5)*x/2) ). (End)

A105438 Triangle, row sums = (Fibonacci numbers - 2).

Original entry on oeis.org

1, 2, 1, 3, 2, 1, 4, 4, 2, 1, 5, 6, 5, 2, 1, 6, 9, 8, 6, 2, 1, 7, 12, 14, 10, 7, 2, 1, 8, 16, 20, 20, 12, 8, 2, 1, 9, 20, 30, 30, 27, 14, 9, 2, 1, 10, 25, 40, 50, 42, 35, 16, 10, 2, 1, 11, 30, 55, 70, 77, 56, 44, 18, 11, 2, 1
Offset: 0

Views

Author

Gary W. Adamson, Apr 09 2005

Keywords

Comments

Row sums = 1, 3, 6, 11, 19, 32, 53...(Fibonacci numbers - 2; starting with F(4)) The first few rows of the triangle are:
Row sums = (Fibonacci numbers - 2; starting 1, 3, 6...).
Column 1 = A002620; Column 2 = A006918; Column 3 = A096338.
Inverse array is A105522. - Paul Barry, Apr 11 2005
Diagonal sums are A027383(n). - Philippe Deléham, Jan 16 2014

Examples

			Column 2: 1, 2, 5, 8, 14, 20, 30...is generated by using the partial sum operator on 1, 1, 3, 3, 6, 6, 10, 10...
The first few rows of the triangle are:
  1;
  2, 1;
  3, 2, 1;
  4, 4, 2, 1;
  5, 6, 5, 2, 1;
  6, 9, 8, 6, 2, 1;
  7, 12, 14, 10, 7, 2, 1;
  8, 16, 20, 20, 12, 8, 2, 1;
  9, 20, 30, 30, 27, 14, 9, 2, 1;
  10, 25, 40, 50, 42, 35, 16, 10, 2, 1;
  ...
		

Crossrefs

Formula

By columns (k = 0, 1, 2...); use partial sum operator on (bin(n, k) numbers repeated).
T(n,k) = Sum_{j=0..n-k} C((j+2k)/2, k)*(1+(-1)^j)+C((j-1+2k)/2, k)*(1-(-1)^j)/2; Riordan array (1/(1-x)^2, x/(1-x^2)). - Paul Barry, Apr 11 2005
T(n,k) = T(n-1,k)+T(n-1,k-1)+T(n-2,k)-T(n-2,k-1)-T(n-3,k), T(0,0)=1, T(1,0)=2, T(1,1)= 1, T(n,k)= 0 if k<0 or if k>n. - Philippe Deléham, Jan 16 2014

A181631 Triangle by rows, number of leading 1's in the maximal Fibonacci representation (A104326).

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 1, 1, 2, 3, 4, 1, 1, 1, 2, 2, 3, 4, 5, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 5, 6, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 5, 6, 7, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 5, 5, 6, 7, 8
Offset: 1

Views

Author

Gary W. Adamson, Nov 02 2010

Keywords

Comments

Row sums = A001911: (1, 3, 6, 11, 19, 32, ...).
A112310 = number of 1's in the maximal Fibonacci representation, which has headings of (..., 8, 5, 3, 2, 1) filling entries from the right to left; as opposed to the minimal Fibonacci representation (A014417) which starts from the left. For example, 8 in maximal = 1011 = (5 + 2 + 1) whereas in minimal = (10000) = (8).
Rows have (1, 2, 3, 5, 8, ...) terms.

Examples

			First few rows of the triangle:
  1;
  1, 2;
  1, 2, 3;
  1, 1, 2, 3, 4;
  1, 1, 1, 2, 2, 3, 4, 5;
  1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 5, 6;
  ...
Example: a(14) = 1 since 14 in the maximal Fibonacci representation is 10111.
		

Crossrefs

Cf. A000045 (row lengths), A003754, A001911 (row sums), A014417, A090996, A104326, A112310.

Programs

  • Mathematica
    f[s_] := Module[{i = FirstPosition[s, 0]}, If[MissingQ[i], Length[s], i[[1]] - 1]]; f /@ Select[IntegerDigits[#, 2] & /@ Range[300], SequencePosition[#, {0, 0}] == {} &] (* Amiram Eldar, May 31 2025 *)

Formula

a(n) = A090996(A003754(n+1)). - Amiram Eldar, May 31 2025

Extensions

More terms from Amiram Eldar, May 31 2025

A054469 a(n) = a(n-1) + a(n-2) + (n+2)*binomial(n+3, 3)/2, with a(0) = 1, a(1) = 7.

Original entry on oeis.org

1, 7, 28, 85, 218, 499, 1053, 2092, 3970, 7272, 12958, 22596, 38739, 65535, 109714, 182185, 300620, 493635, 807555, 1317360, 2144396, 3485032, 5657028, 9174560, 14869613, 24088399, 39009168, 63156437, 102233030, 165466347, 267786673
Offset: 0

Views

Author

Barry E. Williams, Mar 31 2000

Keywords

References

  • A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 194-196.

Crossrefs

Right-hand column 11 of triangle A011794.

Programs

  • Magma
    A054469:= func< n | Fibonacci(n+12) -(1/12)*(1716 +802*n +173*n^2 +20*n^3 +n^4) >;
    [A054469(n): n in [0..40]]; // G. C. Greubel, Oct 21 2024
    
  • Mathematica
    RecurrenceTable[{a[0]==1,a[1]==7,a[n]==a[n-1]+a[n-2]+(n+2) Binomial[ n+3,3]/2},a,{n,30}] (* Harvey P. Dale, Sep 22 2013 *)
    CoefficientList[Series[(1+x)/((1-x)^5*(1-x-x^2)), {x, 0, 40}], x] (* Vincenzo Librandi, Sep 23 2013 *)
  • PARI
    a(n) = sum(i=1,(n+2)\2,binomial(n+5-i,n+2-2*i))+2*sum(i=1,(n+1)\2,binomial(n+5-i,n+1-2*i)) \\ Jason Yuen, Aug 13 2024
    
  • SageMath
    def A054469(n): return fibonacci(n+12) - (1716 + 802*n + 173*n^2 + 20*n^3 + n^4)//12
    [A054469(n) for n in range(41)] # G. C. Greubel, Oct 21 2024

Formula

a(n) = a(n-1) + a(n-2) + (n+1)*(n+2)^2*(n+3)/12.
a(-n) = 0.
a(n) = (Sum_{i=1..floor((n+2)/2)} binomial(n+5-i, n+2-2*i)) + 2*(Sum_{i=1..floor((n+1)/2)} binomial(n+5-i, n+1-2*i)).
G.f.: (1+x) / ((1-x)^5*(1-x-x^2)). - Colin Barker, Jun 11 2013
From G. C. Greubel, Oct 21 2024: (Start)
a(n) = Fibonacci(n+12) - Sum_{j=0..4} Fibonacci(11-2*j) * binomial(n+j, j).
a(n) = Fibonacci(n+12) - (1/12)*(1716 + 802*n + 173*n^2 + 20*n^3 + n^4). (End)

A129713 Triangle read by rows: T(n,k) is the number of Fibonacci binary words of length n and starting with exactly k 1's (0<=k<=n). A Fibonacci binary word is a binary word having no 00 subword.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 1, 5, 3, 2, 1, 1, 1, 8, 5, 3, 2, 1, 1, 1, 13, 8, 5, 3, 2, 1, 1, 1, 21, 13, 8, 5, 3, 2, 1, 1, 1, 34, 21, 13, 8, 5, 3, 2, 1, 1, 1, 55, 34, 21, 13, 8, 5, 3, 2, 1, 1, 1, 89, 55, 34, 21, 13, 8, 5, 3, 2, 1, 1, 1, 144, 89, 55, 34, 21, 13, 8, 5, 3, 2, 1, 1, 1, 233, 144
Offset: 0

Views

Author

Emeric Deutsch, May 12 2007

Keywords

Comments

Row sums are the Fibonacci numbers (A000045). Sum(k*T(n,k), 0<=k<=n) = F(n+3)-2 = A001911(n).

Examples

			T(6,2) = 3 because we have 110110, 110111, 110101.
Triangle starts:
1;
1,1;
1,1,1;
2,1,1,1;
3,2,1,1,1;
5,3,2,1,1,1;
8,5,3,2,1,1,1;
		

Crossrefs

Cf. A054123.
Cf. A007298. - Altug Alkan, May 03 2016

Programs

  • Haskell
    a129713 n k = a129713_tabl !! n !! k
    a129713_row n = a129713_tabl !! n
    a129713_tabl = [1] : [1, 1] : f [1] [1, 1] where
       f us vs = ws : f vs ws where
                 ws = zipWith (+) (init us ++ [0, 0, 0]) (vs ++ [1])
    -- Reinhard Zumkeller, May 26 2015
  • Maple
    with(combinat): T:=proc(n,k) if k<=n-2 then fibonacci(n-k) elif k=n-1 or k=n then 1 else 0 fi end: for n from 0 to 15 do seq(T(n,k),k=0..n) od; # yields sequence in triangular form
  • Mathematica
    nn=15;a=1/(1-y x);b=1/(1-x);Map[Select[#,#>0&]&,CoefficientList[Series[a (1+x)/(1-x^2b),{x,0,nn}],{x,y}]]//Grid (* Geoffrey Critzer, Dec 04 2013 *)

Formula

T(n,k) = F(n-k) if k<=n-2, T(n,n-1) = T(n,n) = 1, where F(j) are the Fibonacci numbers (F(0)=0, F(1)=1). G.f.: G(t,z) = (1-z^2)/[(1-z-z^2)(1-tz)].
a(n) = A007298(n+4) - A007298(n+3). - Altug Alkan, May 03 2016

A166472 a(n) = 2^F(n+2)*3^F(n+1)/12, where F(n) is the n-th Fibonacci number (A000045(n)).

Original entry on oeis.org

1, 6, 72, 5184, 4478976, 278628139008, 14975624970497949696, 50071566192138943522512952098816, 8998235963747242817865410245394871488270255869919232
Offset: 1

Views

Author

Matthew Vandermast, Nov 05 2009

Keywords

Crossrefs

Programs

  • Magma
    [2^(Fibonacci(n+2)-2)*3^(Fibonacci(n+1)-1): n in [1..12]]; // G. C. Greubel, Jul 30 2024
    
  • Mathematica
    Table[(2^Fibonacci[n+2]*3^Fibonacci[n+1])/12, {n,12}] (* G. C. Greubel, May 15 2016 *)
    (3^#[[1]] 2^#[[2]])/12&/@Partition[Fibonacci[Range[2,15]],2,1] (* Harvey P. Dale, Jul 12 2021 *)
  • SageMath
    [2^(fibonacci(n+2)-2)*3^(fibonacci(n+1)-1) for n in range(1,13)] # G. C. Greubel, Jul 30 2024

Formula

a(n) = A166470(n+1)/12.
a(n) = 12*a(n-1)*a(n-2), for n > 1, with a(0) = 1/2, a(1) = 1.
A166469(A002110(m)*a(n)) = Fibonacci(m+n+1), for m > 1.
A166469(a(n)) = Fibonacci(n+3) - 2 = A001911(n).

A168193 a(n) = a(n-1) + a(n-2) + 4, with a(0)=0, a(1)=2.

Original entry on oeis.org

0, 2, 6, 12, 22, 38, 64, 106, 174, 284, 462, 750, 1216, 1970, 3190, 5164, 8358, 13526, 21888, 35418, 57310, 92732, 150046, 242782, 392832, 635618, 1028454, 1664076, 2692534, 4356614, 7049152, 11405770, 18454926, 29860700, 48315630, 78176334, 126491968
Offset: 0

Views

Author

Geoff Ahiakwo, Nov 19 2009

Keywords

Programs

Formula

From R. J. Mathar, Nov 22 2009: (Start)
a(n)= 2*a(n-1) - a(n-3) = 2*A001911(n).
G.f.: 2*x*(1+x)/((x-1)*(x^2+x-1)). (End)
a(n) = a(n-1) + 2*Fibonacci(n+1), with a(0)=0. - Taras Goy, Mar 24 2019
E.g.f.: 4*exp(x/2)*(5*cosh(sqrt(5)*x/2) + 2*sqrt(5)*sinh(sqrt(5)*x/2))/5 - 4*exp(x). - Stefano Spezia, Oct 14 2022
a(n) = A019274(n+1)+A019274(n+2). - R. J. Mathar, Jul 07 2023

Extensions

Definition replaced by recurrence from R. J. Mathar, Nov 23 2009
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