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 1-8 of 8 results.

A074062 Reflected (see A074058) pentanacci numbers A074048.

Original entry on oeis.org

5, -1, -1, -1, -1, 9, -7, -1, -1, -1, 19, -23, 5, -1, -1, 39, -65, 33, -7, -1, 79, -169, 131, -47, 5, 159, -417, 431, -225, 57, 313, -993, 1279, -881, 339, 569, -2299, 3551, -3041, 1559, 799, -5167, 9401, -9633, 6159, 39, -11133, 23969, -28667, 21951, -6081, -22305
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Aug 17 2002

Keywords

Comments

a(n) is also the trace of A^(-n), where A is the matrix ( (1,1,0,0,0), (1,0,1,0,0), (1,0,0,1,0), (1,0,0,0,1), (1,0,0,0,0) ).
a(n) is also the sum of determinants of 4th-order principal minors of A^n.

Crossrefs

Programs

  • Magma
    I:=[5,-1,-1,-1,-1]; [n le 5 select I[n] else (-1)*(Self(n-1) +Self(n-2) +Self(n-3) +Self(n-4)) + Self(n-5): n in [1..61]]; // G. C. Greubel, Jul 05 2021
    
  • Mathematica
    CoefficientList[Series[(5+4*x+3*x^2+2*x^3+x^4)/(1+x+x^2+x^3+x^4-x^5), {x, 0, 60}], x]
  • PARI
    Vec((5+4*x+3*x^2+2*x^3+x^4)/(1+x+x^2+x^3+x^4-x^5) + O(x^60)) \\ Michel Marcus, Sep 14 2020
    
  • Sage
    def A074062_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (5+4*x+3*x^2+2*x^3+x^4)/(1+x+x^2+x^3+x^4-x^5) ).list()
    A074062_list(60) # G. C. Greubel, Jul 05 2021

Formula

a(n) = -a(n-1) -a(n-2) -a(n-3) -a(n-4) +a(n-5), a(0)=5, a(1)=-1, a(2)=-1, a(3)=-1, a(4)=-1.
G.f.: (5 +4*x +3*x^2 +2*x^3 +x^4)/(1 +x +x^2 +x^3 +x^4 -x^5).

Extensions

More terms from Michel Marcus, Sep 14 2020

A075129 Binomial transform of reflected tetranacci numbers A074058: a(n)=Sum((-1)^k Binomial(n,k)*A074058(k),(k=0,..,n)).

Original entry on oeis.org

4, 5, 5, 5, 13, 50, 155, 390, 861, 1805, 3850, 8640, 20167, 47520, 110780, 254450, 579149, 1316485, 3003095, 6878765, 15790278, 36245235, 83101760, 190322935, 435678591, 997445500, 2284365660, 5233190405, 11989714652, 27467989310
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Sep 03 2002

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(4-15*z+20*z^2-10*z^3)/(1-5*z+10*z^2-10*z^3+3*z^4), {z, 0, 30}], z]
    LinearRecurrence[{5,-10,10,-3},{4,5,5,5},30] (* Harvey P. Dale, Jan 26 2025 *)

Formula

a(n)=5a(n-1)-10a(n-2)+10a(n-3)-3a(n-4), a(0)=4, a(1)=5, a(2)=5, a(3)=5. G.f.: (4 - 15*z + 20*z^2 - 10*z^3)/(1 - 5*z + 10*z^2 - 10*z^3 + 3*z^4).

A057597 a(n) = -a(n-1) - a(n-2) + a(n-3), a(0)=0, a(1)=0, a(2)=1.

Original entry on oeis.org

0, 0, 1, -1, 0, 2, -3, 1, 4, -8, 5, 7, -20, 18, 9, -47, 56, 0, -103, 159, -56, -206, 421, -271, -356, 1048, -963, -441, 2452, -2974, 81, 5345, -8400, 3136, 10609, -22145, 14672, 18082, -54899, 51489, 21492, -127880, 157877, -8505, -277252, 443634, -174887, -545999, 1164520, -793408, -917111
Offset: 0

Views

Author

N. J. A. Sloane, Oct 06 2000

Keywords

Comments

Reflected (A074058) tribonacci numbers A000073: A000073(n) = a(1-n).
There is an alternative way to produce this sequence, from A000073, which is 0,0,1,1,2,4,7,13,24,44,... Call this {b(n)}. Taking x1 = (b(2))^2 - b(1)*b(3) = 0; x2 = (b(3))^2 - b(2)*b(4) = 1; x3 = (b(4))^2 - b(3)*b(5) = -1; x4 = 0, x5 = 2, we generate (0),0,1,-1,0,2,-3,1. - John McNamara, Jan 02 2004
Pisano period lengths: 1, 4, 13, 8, 31, 52, 48, 16, 39, 124, 110, 104, 168, 48, 403, 32, 96, 156, 360, 248, ... - R. J. Mathar, Aug 10 2012
The negative powers of the tribonacci constant t = A058265 are t^(-n) = a(n+1)*t^2 + b(n)*t + a(n+2)*1, for n >= 0, with b(n) = A319200(n) = -(a(n+1) - a(n)), for n >= 0. 1/t = t^2 - t - 1 = A192918. See the example in A319200 for the first powers. - Wolfdieter Lang, Oct 23 2018

References

  • Petho Attila, Posting to Number Theory List (NMBRTHRY(AT)LISTSERV.NODAK.EDU), Oct 06 2000.

Crossrefs

Cf. A000073, A058265, A319200. First differences of A077908.

Programs

  • GAP
    a:=[0,0,1];;  for n in [4..55] do a[n]:=-a[n-1]-a[n-2]+a[n-3]; od; a; # Muniru A Asiru, Oct 23 2018
  • Haskell
    a057597 n = a057597_list !! n
    a057597_list = 0 : 0 : 1 : zipWith3 (\x y z -> - x - y + z)
                   (drop 2 a057597_list) (tail a057597_list) a057597_list
    -- Reinhard Zumkeller, Oct 07 2012
    
  • Maple
    seq(coeff(series(x^2/(1+x+x^2-x^3),x,n+1), x, n), n = 0 .. 50); # Muniru A Asiru, Oct 23 2018
  • Mathematica
    CoefficientList[Series[x^2/(1+x+x^2-x^3), {x, 0, 50}], x]
  • PARI
    {a(n) = polcoeff( if( n<0, x / ( 1 - x - x^2 - x^3), x^2 / ( 1 + x + x^2 - x^3) ) + x*O(x^abs(n)), abs(n))} /* Michael Somos, Sep 03 2007 */
    

Formula

G.f.: x^2/(1+x+x^2-x^3).
G.f.: Q(0)*x^2/2, where Q(k) = 1 + 1/(1 - x*(4*k+1 + x - x^2)/( x*(4*k+3 + x - x^2) - 1/Q(k+1) )); (continued fraction). - Sergei N. Gladkovskii, Sep 09 2013
G.f. -x*T(1/x), where T is the g.f. of A000073. - Wolfdieter Lang, Oct 26 2018

Extensions

Deleted certain dangerous or potentially dangerous links. - N. J. A. Sloane, Jan 30 2021

A073145 a(n) = -a(n-1) - a(n-2) + a(n-3), a(0)=3, a(1)=-1, a(2)=-1.

Original entry on oeis.org

3, -1, -1, 5, -5, -1, 11, -15, 3, 23, -41, 21, 43, -105, 83, 65, -253, 271, 47, -571, 795, -177, -1189, 2161, -1149, -2201, 5511, -4459, -3253, 13223, -14429, -2047, 29699, -42081, 10335, 61445, -113861, 62751, 112555, -289167, 239363, 162359, -690889, 767893, 85355
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Jul 17 2002

Keywords

Comments

Previous name was: Sum of the determinants of the principal minors of 2nd order of n-th power of Tribomatrix: first row (1, 1, 0); second row (1, 0, 1); third row (1, 0, 0).
a(n) is related to the generalized Lucas numbers S(n). For instance, 2S(n) = a(n)^2 - a(2n).
a(n) is also the reflected (A074058) sequence of the generalized tribonacci sequence (A001644).

Examples

			G.f. = 3 - x - x^2 + 5*x^3 - 5*x^4 - x^5 + 11*x^6 - 15*x^7 + 3*x^8 + 23*x^9 + ...
		

Crossrefs

Programs

  • Magma
    I:=[3,-1,-1]; [n le 3 select I[n] else -Self(n-1)-Self(n-2)+Self(n-3): n in [1..50]]; // Vincenzo Librandi, Aug 17 2013
    
  • Mathematica
    A = Table[0, {3}, {3}]; A[[1, 1]] = 1; A[[1, 2]] = 1; A[[2, 1]] = 1; A[[2, 3]] = 1; A[[3, 1]] = 1; For[i = 1; t = IdentityMatrix[3], i < 50, i++, t = t.A; Print[t[[2, 2]]*t[[3, 3]] - t[[2, 3]]*t[[3, 2]] + t[[1, 1]]*t[[3, 3]] - t[[1, 3]]*t[[3, 1]] + t[[1, 1]]*t[[2, 2]] - t[[1, 2]]*t[[2, 1]]]]
    LinearRecurrence[{-1, -1, 1}, {3, -1, -1}, 50] (* Vincenzo Librandi, Aug 17 2013 *)
    nxt[{a_,b_,c_}]:={b,c,a-b-c}; NestList[nxt,{3,-1,-1},50][[;;,1]] (* Harvey P. Dale, Jun 16 2024 *)
  • PARI
    {a(n) = if( n<0, polsym(1 + x+ x^2 - x^3, -n)[-n+1], polsym(1 - x - x^2 - x^3, n)[n+1])}; /* Michael Somos, Dec 17 2016 */
    
  • PARI
    a(n)=([0,1,0; 0,0,1; 1,-1,-1]^n*[3;-1;-1])[1,1] \\ Charles R Greathouse IV, Feb 07 2017
    
  • Sage
    ((3+2*x+x^2)/(1+x+x^2-x^3)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Apr 22 2019

Formula

a(n) = -a(n-1) - a(n-2) + a(n-3), a(0)=3, a(1)=-1, a(2)=-1.
O.g.f.: (3 + 2*x + x^2)/(1 + x + x^2 - x^3).
a(n) = -T(n)^2 + 2*T(n-1)^2 + 3*T(n-2)^2 - 2*T(n)*T(n-1) + 2*T(n)*T(n-2) + 4*T(n-1)*T(n-2), where T(n) are tribonacci numbers (A000073).
a(n) = 3*A057597(n+2) + 2*A057597(n+1) + A057597(n). - R. J. Mathar, Jun 06 2011
From Peter Bala, Jun 29 2015: (Start)
a(n) = alpha^n + beta^n + gamma^n, where alpha, beta and gamma are the roots of 1 - x - x^2 - x^3 = 0.
x^2*exp( Sum_{n >= 1} a(n)*x^n/n ) = x^2 - x^3 + 2*x*5 - 3*x^6 + x^7 + ... is the o.g.f. for A057597. (End)
a(n) = A001644(-n) for all n in Z. - Michael Somos, Dec 17 2016

Extensions

Better name by Joerg Arndt, Aug 17 2013
More terms from Vincenzo Librandi, Aug 17 2013
Deleted certain dangerous or potentially dangerous links. - N. J. A. Sloane, Jan 30 2021

A073937 a(n) = a(n-1) - a(n-2) + a(n-3) + a(n-4), a(0)=4, a(1)=1, a(2)=-1, a(3)=1.

Original entry on oeis.org

4, 1, -1, 1, 7, 6, -1, 1, 15, 19, 4, 1, 31, 53, 27, 6, 63, 137, 107, 39, 132, 337, 351, 185, 303, 806, 1039, 721, 791, 1915, 2884, 2481, 2303, 4621, 7683, 7846, 7087, 11545, 19987, 23375, 22020, 30177, 51519, 66737, 67415, 82374, 133215, 184993, 201567, 232163, 348804
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Aug 13 2002

Keywords

Comments

From Kai Wang, Nov 03 2020: (Start)
Let f(x) = x^4 - x^3 - x^2 - x - 1 and {x1,x2,x3,x4} be the roots of f(x). Then a(n) = (x1*x2*x3)^n + (x1*x2*x4)^n + (x1*x3*x4)^n + (x2*x3*x4)^n.
Let g(y) = y^4 - y^3 + y^2 - y - 1 and {y1,y2,y3,y4} be the roots of g(y). Then a(n) = y1^n + y2^n + y3^n + y4^n. (End)

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(4-3*x+2*x^2-x^3)/(1-x+x^2-x^3-x^4), {x, 0, 50}], x]
    LinearRecurrence[{1,-1,1,1},{4,1,-1,1},60] (* Harvey P. Dale, Sep 05 2021 *)
  • PARI
    polsym(y^4 - y^3 + y^2 - y - 1, 55) \\ Joerg Arndt, Nov 07 2020

Formula

G.f.: (4 - 3*x + 2*x^2 - x^3)/(1 - x + x^2 - x^3 - x^4).
From Kai Wang, Nov 03 2020: (Start)
For n >= 1, a(n) = Sum_{j1,j2,j3,j4>=0; j1+2*j2+3*j3+4*j4=n} (-1)^j2*n*(j1+j2+j3+j4-1)!/(j1!*j2!*j3!*j4!).
For n > 1, a(n) = (-1)^n*(4*A100329(n+1) + 3*A100329(n) + 2*A100329(n-1) + A100329(n-2)). (End)
From Peter Bala, Jan 19 2023: (Start)
a(n) = (-1)^n*A074058(n).
a(n) = trace of M^n, where M is the 4 X 4 matrix [[0, 0, 0, -1], [-1, 0, 0, 1], [0, -1, 0, 1], [0, 0, -1, 1]].
The Gauss congruences hold: a(n*p^r) == a(n*p^(r-1)) (mod p^k) for positive integers n and r and all primes p. See Zarelua. (End)

A074453 Sum of determinants of 2nd order principal minors of powers of inverse of the matrix ((1,1,0,0),(1,0,1,0),(1,0,0,1),(1,0,0,0)).

Original entry on oeis.org

6, 1, -3, 1, 17, 16, -15, -13, 81, 127, -58, -175, 329, 885, -31, -1424, 833, 5543, 2181, -9233, -2298, 31025, 27893, -49495, -54879, 150416, 245697, -204965, -526887, 570895, 1801670, -407711, -3882303, 946397, 11542929, 3442672, -24121039, -10317745, 64959629, 56727711, -127083514
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Aug 22 2002

Keywords

Comments

a(n) is the reflected (A074058) sequence of sequence A074193.

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(6-5*x+8*x^2-6*x^3-4*x^4-x^5)/(1-x+2*x^2-2*x^3-2*x^4-x^5-x^6), {x, 0, 40}], x]
    LinearRecurrence[{1,-2,2,2,1,1},{6,1,-3,1,17,16},50] (* Harvey P. Dale, Mar 16 2012 *)

Formula

a(n)=a(n-1)-2a(n-2)+2a(n-3)+2a(n-4)+a(n-5)+a(n-6).
G.f.: (6-5x+8x^2-6x^3-4x^4-x^5)/(1-x+2x^2-2x^3-2x^4-x^5-x^6).
abs(a(n)) = abs(A074193(n)). - Joerg Arndt, Oct 22 2020

A074585 a(n)= Sum_{j=0..floor(n/2)} A073145(2*j + q), where q = 2*(n/2 - floor(n/2)).

Original entry on oeis.org

3, -1, 2, 4, -3, 3, 8, -12, 11, 11, -30, 32, 13, -73, 96, -8, -157, 263, -110, -308, 685, -485, -504, 1676, -1653, -525, 3858, -4984, 605, 8239, -13824, 6192, 15875, -35889, 26210, 25556, -87651, 88307, 24904, -200860, 264267, -38501, -426622
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Aug 28 2002

Keywords

Comments

a(n) is the convolution of A073145(n) with the sequence (1,0,1,0,1,0, ...).
a(n) is also the sum of the reflected (see A074058) sequence of the generalized tribonacci sequence (A001644).

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 50); Coefficients(R!( (3+2*x+x^2)/(1+x-2*x^3-x^4+x^5) )); // G. C. Greubel, Apr 13 2019
    
  • Mathematica
    CoefficientList[ Series[(3+2*x+x^2)/(1+x-2*x^3-x^4+x^5), {x, 0, 50}], x]
  • PARI
    my(x='x+O('x^50)); Vec((3+2*x+x^2)/(1+x-2*x^3-x^4+x^5)) \\ G. C. Greubel, Apr 13 2019
    
  • Sage
    ((3+2*x+x^2)/(1+x-2*x^3-x^4+x^5)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Apr 13 2019

Formula

a(n) = -a(n-1) + 2*a(n-3) + a(n-4) - a(n-5), a(0) = 3, a(1) = -1, a(2) = 2, a(3) = 4, a(4) = -3.
G.f.: (3 + 2*x + x^2)/(1 + x - 2*x^3 - x^4 + x^5).

Extensions

More terms from Robert G. Wilson v, Aug 29 2002

A331890 a(n) = -a(n-1) - a(n-2) + 2*a(n-3) with a(0)=3, a(1)=-1, a(2)=-1.

Original entry on oeis.org

3, -1, -1, 8, -9, -1, 26, -43, 15, 80, -181, 131, 210, -703, 755, 368, -2529, 3671, -406, -8323, 16071, -8560, -24157, 64859, -57822, -55351, 242891, -303184, -50409, 839375, -1395334, 455141, 2618943, -5864752, 4156091, 6946547, -22832142, 24197777
Offset: 0

Views

Author

Wojciech Florek, Jan 30 2020

Keywords

Comments

a(n) is the reflected sequence (cf. A074058) of the generalized tribonacci sequence b(n) with b(0) = 3 and b(n) = A186575(n-1) for n > 0.

Crossrefs

Programs

  • Magma
    a:=[3,-1,-1]; [n le 3 select a[n] else -Self(n-1)-Self(n-2)+2*Self(n-3):n in [1..30]]; // Marius A. Burtea, Feb 02 2020
  • Mathematica
    LinearRecurrence[{-1,-1,2},{3,-1,-1},38] (* Stefano Spezia, Jan 31 2020 *)

Formula

G.f.: (3 + 2*x + x^2)/(1 + x + x^2 - 2*x^3).
a(n) = 3*A077975(n)+2*A077975(n-1)+A077975(n-2). - R. J. Mathar, Feb 28 2020

Extensions

Definition clarified by N. J. A. Sloane, Apr 23 2020
Showing 1-8 of 8 results.