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.

Showing 1-7 of 7 results.

A214984 Array: T(m,n) = (F(m) + F(2*m) + ... + F(n*m))/F(m), by antidiagonals, where F = A000045 (Fibonacci numbers).

Original entry on oeis.org

1, 2, 1, 4, 4, 1, 7, 12, 5, 1, 12, 33, 22, 8, 1, 20, 88, 94, 56, 12, 1, 33, 232, 399, 385, 134, 19, 1, 54, 609, 1691, 2640, 1487, 342, 30, 1, 88, 1596, 7164, 18096, 16492, 6138, 872, 48, 1, 143, 4180, 30348, 124033, 182900, 110143, 25319, 2256, 77, 1
Offset: 1

Views

Author

Clark Kimberling, Oct 28 2012

Keywords

Comments

col 1: A001612 (except for initial term)
row 1: A000071
row 2: A027941
row 3: A049652
row 4: A092521
row 6: A049664
row 8: A156093 without minus signs

Examples

			Northwest corner:
1...2....4.....7......12......20
1...4....12....33.....88......232
1...5....22....94.....399.....1691
1...8....56....385....2640....18096
1...12...134...1487...16492...182900
		

Crossrefs

Programs

  • Mathematica
    F[n_] := Fibonacci[n]; L[n_] := LucasL[n];
    t[m_, n_] := (1/F[m])*Sum[F[m*k], {k, 1, n}]
    TableForm[Table[t[m, n], {m, 1, 10}, {n, 1, 10}]]
    Flatten[Table[t[k, n + 1 - k], {n, 1, 12}, {k, 1, n}]]

Formula

For odd-numbered rows (m odd):
T(m,n) = (F(m*n+m) + F(m*n) - F(m))/(F(m)*L(m)).
For even-numbered rows (m even):
T(m,n) = (F(m*n+m) - F(m*n) - F(m))/(F(m)*(L(m)-2)).

A156086 Sum of the squares of the first n Fibonacci numbers with index divisible by 4.

Original entry on oeis.org

0, 9, 450, 21186, 995355, 46760580, 2196752004, 103200583725, 4848230683206, 227763641527110, 10700042921091135, 502674253649756424, 23614989878617461000, 1109401850041370910801, 52118271962065815346890, 2448449380367051950393290
Offset: 0

Views

Author

Stuart Clary, Feb 04 2009

Keywords

Comments

Natural bilateral extension (brackets mark index 0): ..., -21186, -450, -9, 0, [0], 9, 450, 21186, 995355, ... This is (-A156086)-reversed followed by A156086. That is, A156086(-n) = -A156086(n-1).

Crossrefs

Programs

  • Mathematica
    a[n_Integer] := If[ n >= 0, Sum[ Fibonacci[4k]^2, {k, 1, n} ], -Sum[ Fibonacci[-4k]^2, {k, 1, -n - 1} ] ]

Formula

Let F(n) be the Fibonacci number A000045(n).
a(n) = sum_{k=1..n} F(4k)^2.
Closed form: a(n) = F(8n+4)/15 - (2n + 1)/5.
Recurrence: a(n) - 48 a(n-1) + 48 a(n-2) - a(n-3) = 18.
Recurrence: a(n) - 49 a(n-1) + 96 a(n-2) - 49 a(n-3) + a(n-4) = 0.
G.f.: A(x) = (9 x + 9 x^2)/(1 - 49 x + 96 x^2 - 49 x^3 + x^4) = 9 x (1 + x)/((1 - x)^2 (1 - 47 x + x^2)).

A156087 One ninth of the sum of the squares of the first n Fibonacci numbers with index divisible by 4.

Original entry on oeis.org

0, 1, 50, 2354, 110595, 5195620, 244083556, 11466731525, 538692298134, 25307071280790, 1188893657899015, 55852694849972936, 2623887764290829000, 123266872226818990089, 5790919106896201705210, 272049931151894661154810
Offset: 0

Views

Author

Stuart Clary, Feb 04 2009

Keywords

Comments

Natural bilateral extension (brackets mark index 0): ..., -110595, -2354, -50, -1, 0, [0], 1, 50, 2354, 110595, 5195620, ... This is (-A156087)-reversed followed by A156087. That is, A156087(-n) = -A156087(n-1).

Crossrefs

Programs

  • Mathematica
    a[n_Integer] := If[ n >= 0, Sum[ (1/9) Fibonacci[4k]^2, {k, 1, n} ], -Sum[ (1/9) Fibonacci[-4k]^2, {k, 1, -n - 1} ] ]
    Accumulate[Fibonacci[4Range[0,20]]^2]/9 (* Harvey P. Dale, Sep 22 2011 *)

Formula

Let F(n) be the Fibonacci number A000045(n).
a(n) = sum_{k=1..n} F(4k)^2.
Closed form: a(n) = F(8n+4)/135 - (2n + 1)/45.
Recurrence: a(n) - 48 a(n-1) + 48 a(n-2) - a(n-3) = 2.
Recurrence: a(n) - 49 a(n-1) + 96 a(n-2) - 49 a(n-3) + a(n-4) = 0.
G.f.: A(x) = (x + x^2)/(1 - 49 x + 96 x^2 - 49 x^3 + x^4) = x (1 + x)/((1 - x)^2 (1 - 47 x + x^2)).

A156092 Alternating sum of the squares of the first n Fibonacci numbers with index divisible by 4.

Original entry on oeis.org

0, -9, 432, -20304, 953865, -44811360, 2105180064, -98898651657, 4646131447824, -218269279396080, 10254010000167945, -481720200728497344, 22630595424239207232, -1063156264738514242569, 49945713847285930193520, -2346385394557700204852880
Offset: 0

Views

Author

Stuart Clary, Feb 04 2009

Keywords

Comments

Natural bilateral extension (brackets mark index 0): ..., -953865, 20304, -432, 9, 0, [0], -9, 432, -20304, 953865, -44811360, ... This is (-A156092)-reversed followed by A156092. That is, A156092(-n) = -A156092(n-1).

Crossrefs

Programs

  • Mathematica
    a[n_Integer] := If[ n >= 0, Sum[ (-1)^k Fibonacci[4k]^2, {k, 1, n} ], Sum[ -(-1)^k Fibonacci[-4k]^2, {k, 1, -n - 1} ] ]

Formula

Let F(n) be the Fibonacci number A000045(n) and let L(n) be the Lucas number A000032(n).
a(n) = sum_{k=1..n} (-1)^k F(4k)^2.
Closed form: a(n) = (-1)^n (L(8n+4) - 7)/35.
Factored closed form: a(n) = (-1)^n F(4n) F(4n+4)/7.
Recurrence: a(n) + 47 a(n-1) + a(n-2) = (-1)^n 9.
Recurrence: a(n) + 48 a(n-1) + 48 a(n-2) + a(n-3) = 0.
G.f.: A(x) = -9 x/(1 + 48 x + 48 x^2 + x^3) = -9 x/((1 + x)(1 + 47 x + x^2)).

A161582 The list of the k values in the common solutions to the 2 equations 5*k+1=A^2, 9*k+1=B^2.

Original entry on oeis.org

0, 7, 336, 15792, 741895, 34853280, 1637362272, 76921173511, 3613657792752, 169764995085840, 7975341111241735, 374671267233275712, 17601574218852716736, 826899317018844410887, 38846666325666834594960, 1824966417989322381552240, 85734574979172485098360327
Offset: 1

Views

Author

Paul Weisenhorn, Jun 14 2009

Keywords

Comments

The 2 equations are equivalent to the Pell equation x^2-45*y^2=1, with x=(45*k+7)/2 and y= A*B/2, case C=5 in A160682.

Crossrefs

Cf. A160682, A049685 (sequence of A), A033890 (sequence of B).

Programs

  • Maple
    t:=0: for n from 0 to 1000000 do a:=sqrt(5*n+1); b:=sqrt(9*n+1);
    if (trunc(a)=a) and (trunc(b)=b) then t:=t+1; print(t,n,a,b): end if: end do:
  • Mathematica
    LinearRecurrence[{48,-48,1},{0,7,336},30] (* or *) Rest[CoefficientList[ Series[ -7x^2/((x-1)(x^2-47x+1)),{x,0,30}],x]] (* Harvey P. Dale, Mar 21 2013 *)

Formula

k(t+3) = 48*(k(t+2)-k(t+1))+k(t).
With w = sqrt(5),
k(t) = ((7+3*w)*((47+21*w)/2)^(t-1)+(7-3*w)*((47-21*w)/2)^(t-1))/90.
k(t) = floor((7+3*w)*((47+21*w)/2)^(t-1)/90) = 7*|A156093(t-1)|.
G.f.: -7*x^2/((x-1)*(x^2-47*x+1)).
a(1)=0, a(2)=7, a(3)=336, a(n) = 48*a(n-1)-48*a(n-2)+a(n-3). - Harvey P. Dale, Mar 21 2013

Extensions

Edited, extended by R. J. Mathar, Sep 02 2009

A214985 Array: T(m,n) = (F(n) + F(2*n) + ... + F(n*m))/F(n), by antidiagonals; transpose of A214984.

Original entry on oeis.org

1, 1, 2, 1, 4, 4, 1, 5, 12, 7, 1, 8, 22, 33, 12, 1, 12, 56, 94, 88, 20, 1, 19, 134, 385, 399, 232, 33, 1, 30, 342, 1487, 2640, 1691, 609, 54, 1, 48, 872, 6138, 16492, 18096, 7164, 1596, 88, 1, 77, 2256, 25319, 110143, 182900, 124033, 30348, 4180, 143
Offset: 1

Views

Author

Clark Kimberling, Oct 28 2012

Keywords

Comments

row 1: A001612 (except for initial term)
col 1: A000071
col 2: A027941
col 3: A049652
col 4: A092521
col 6: A049664
col 8: A156093 without minus signs

Examples

			Northwest corner:
1....1.....1......1.......1
2....4.....5......8.......12
4....12....22.....56......134
7....33....94.....385.....1487
12...88....399....2640....16492
20...232...1691...18096...182900
		

Crossrefs

Programs

  • Mathematica
    F[n_] := Fibonacci[n]; L[n_] := LucasL[n];
    t[m_, n_] := (1/F[n])*Sum[F[k*n], {k, 1, m}]
    TableForm[Table[t[m, n], {m, 1, 10}, {n, 1, 10}]]
    Flatten[Table[t[k, n + 1 - k], {n, 1, 12}, {k, 1, n}]]

Formula

For odd-numbered columns (m odd):
T(m,n) = (F(m*n+m) + F(m*n) - F(m))/(F(m)*L(m)).
For even-numbered columns (m even):
T(m,n) = (F(m*n+m) - F(m*n) - F(m))/(F(m)*(L(m)-1)).

A049654 a(n) = (F(8*n+1) - 1)/3 where F=A000045 (the Fibonacci sequence).

Original entry on oeis.org

0, 11, 532, 25008, 1174859, 55193380, 2592914016, 121811765387, 5722560059188, 268838511016464, 12629687457714635, 593326472001571396, 27873714496616140992, 1309471254868957055243, 61517275264344365455444
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    [(Fibonacci(8*n+1) - 1)/3: n in [0..30]]; // G. C. Greubel, Dec 02 2017
  • Mathematica
    LinearRecurrence[{48, -48, 1}, {0, 11, 532}, 50] (* or *) Table[( Fibonacci[8*n+1]-1)/3, {n,0,30}] (* G. C. Greubel, Dec 02 2017 *)
    CoefficientList[Series[-x(11+4x)/((x-1)(x^2-47*x+1)),{x,0,14}],x] (* Stefano Spezia, Feb 18 2024 *)
  • PARI
    for(n=0,30, print1((fibonacci(8*n+1) - 1)/3, ", ")) \\ G. C. Greubel, Dec 02 2017
    

Formula

From R. J. Mathar, Oct 26 2015: (Start)
G.f.: -x*(11+4*x) / ( (x-1)*(x^2-47*x+1) ).
a(n) = 11*|A156093(n)|+4*|A156093(n-1)|. (End)
Showing 1-7 of 7 results.