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.

Previous Showing 11-18 of 18 results.

A007653 Coefficients of L-series for elliptic curve "37a1": y^2 + y = x^3 - x.

Original entry on oeis.org

1, -2, -3, 2, -2, 6, -1, 0, 6, 4, -5, -6, -2, 2, 6, -4, 0, -12, 0, -4, 3, 10, 2, 0, -1, 4, -9, -2, 6, -12, -4, 8, 15, 0, 2, 12, -1, 0, 6, 0, -9, -6, 2, -10, -12, -4, -9, 12, -6, 2, 0, -4, 1, 18, 10, 0, 0, -12, 8, 12, -8, 8, -6, -8, 4, -30, 8, 0, -6, -4, 9, 0, -1, 2, 3, 0, 5, -12, 4, 8, 9, 18, -15, 6, 0, -4, -18, 0, 4, 24, 2, 4, 12, 18, 0
Offset: 1

Views

Author

Keywords

Comments

G.f. is Fourier series of a weight 2 level 37 modular cusp form.

Examples

			G.f. = q - 2*q^2 - 3*q^3 + 2*q^4 - 2*q^5 + 6*q^6 - q^7 + 6*q^9 + 4*q^10 - 5*q^11 + ...
		

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Magma
    A := Basis( CuspForms( Gamma0(37), 2), 72); A[1] - 2*A[2]; /* Michael Somos, Jan 02 2017 */
    
  • PARI
    {a(n) = if( n<1, 0, ellak( ellinit([ 0, 0, -1, -1, 0]), n))}; /* Michael Somos, Mar 04 2011 */
    
  • PARI
    {a(n) = if( n<1, 0, qfrep([ 2, 1, 0, 1; 1, 8, 1, -3; 0, 1, 10, 2; 1, -3, 2, 12 ], n, 1)[n] - qfrep([ 4, 1, 2, 1; 1, 4, 1, 0; 2, 1, 6, -2; 1, 0, -2, 20 ], n, 1)[n])}; /* Michael Somos, Apr 02 2006 */
    
  • Sage
    def a(n):
        return EllipticCurve("37a1").an(n)  # Robin Visser, Aug 02 2023

Formula

a(3^n) = A000748(n).
a(n) = (A045866(n) - A045867(n)) / 2.
a(n) is multiplicative with a(p^e) = a(p) * a(p^(e-1)) - p * a(p^(e-2)) where a(p) = p+1 - number of solutions of y^2 + y = x^3 - x modulo p including the point at infinity. - Michael Somos, Mar 03 2011
G.f. is a period 1 Fourier series which satisfies f(-1 / (37 t)) = -37 (t/i)^2 f(t) where q = exp(2 Pi i t).

Extensions

More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jun 22 2000

A132677 Period 3: repeat [1, 2, -3].

Original entry on oeis.org

1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3, 1, 2, -3
Offset: 0

Views

Author

Paul Curtz, Nov 15 2007

Keywords

Comments

a(n) is proportional to its 6n-th differences.
Nonsimple continued fraction expansion of 1+sqrt(2/5) = 1.63245553... (see A010494). - R. J. Mathar, Mar 08 2012

Crossrefs

Programs

Formula

G.f.: (1+3*x)/(1+x+x^2). - Jaume Oliver Lafont, Mar 24 2009
a(n) = cos(2*Pi*n/3) + 5*sin(2*Pi*n/3)/sqrt(3). - R. J. Mathar, Oct 08 2011
a(n) + a(n-1) + a(n-2) = 0 for n > 1, a(n) = a(n-3) for n > 2. - Wesley Ivan Hurt, Jul 01 2016

A094715 a(n) = Sum_{2*i+3*j=n, 0<=i<=n, 0<=j<=n} n!/( (2*i)!*(3*j)! ).

Original entry on oeis.org

1, 0, 1, 1, 1, 10, 2, 35, 29, 85, 211, 220, 926, 1001, 3095, 5461, 9829, 25126, 37130, 97223, 164921, 349525, 728575, 1309528, 2973350, 5326685, 11450531, 22369621, 43942081, 91869970, 174174002, 365088395, 708653429, 1431655765, 2884834891
Offset: 0

Views

Author

Benoit Cloitre, May 23 2004

Keywords

Comments

Average of binomial and inverse binomial transform of {1, 0, 0, 1, 0, 0, 1, ...}. - Paul Barry, Jan 04 2005

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 50); Coefficients(R!( (1-2*x^2-x^3+x^4-x^5)/((1-2*x)*(1-x+x^2)*(1+3*x+3*x^2)) )); // G. C. Greubel, Feb 13 2023
    
  • Maple
    A094715_list := proc(n) local i; (exp(z)+2*exp(-z/2)*cos(z*sqrt(3/4)))*cosh(z)/3;  series(%,z,n+2): seq(i!*coeff(%,z,i),i=0..n) end: A094715_list(34); # Peter Luschny, Jul 10 2012
  • Mathematica
    Table[(1/6)*(Boole[n==0] +2^n +2*ChebyshevU[n,1/2] -ChebyshevU[n-1, 1/2] +2*3^(n/2)*ChebyshevU[n, -Sqrt[3]/2] +3^((n+1)/2)*ChebyshevU[n- 1, -Sqrt[3]/2]), {n,0,50}] (* G. C. Greubel, Feb 13 2023 *)
  • PARI
    a(n)=sum(i=0,n,sum(j=0,n,if(n-2*i-3*j,0,n!/(2*i)!/(3*j)!)))
    
  • SageMath
    def A094715_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (1-2*x^2-x^3+x^4-x^5)/((1-2*x)*(1-x+x^2)*(1+3*x+3*x^2)) ).list()
    A094715_list(50) # G. C. Greubel, Feb 13 2023

Formula

Limit_{n --> oo} a(n)/2^n = 1/6.
G.f.: (1-2*x^2-x^3+x^4-x^5)/((1-2*x)*(1-x+x^2)*(1+3*x+3*x^2)). - Vladeta Jovovic, May 23 2004
a(n) = (1/3)*Sum_{k=0..floor(n/2)} C(n, 2*k)*(2*cos(2*Pi*(n-2*k)/3) + 1). - Paul Barry, Jan 04 2005 [corrected by Jason Yuen, Aug 28 2024]
E.g.f.: (exp(z) + 2*exp(-z/2)*cos(z*sqrt(3/4)))*cosh(z)/3. - Peter Luschny, Jul 10 2012
a(n) = (1/6)*([n=0] + 2^n + 2*A010892(n) - A010892(n-1) + 2*A000748(n) + 3*A000748(n-1)). - G. C. Greubel, Feb 13 2023

A168615 Inverse binomial transform of A169609, or of A144437 preceded by 1.

Original entry on oeis.org

1, 2, -2, 0, 6, -18, 36, -54, 54, 0, -162, 486, -972, 1458, -1458, 0, 4374, -13122, 26244, -39366, 39366, 0, -118098, 354294, -708588, 1062882, -1062882, 0, 3188646, -9565938, 19131876, -28697814, 28697814, 0, -86093442, 258280326, -516560652
Offset: 0

Views

Author

Paul Curtz, Dec 01 2009

Keywords

Crossrefs

Programs

  • Magma
    [ n le 2 select n else n eq 3 select -2 else -3*Self(n-1)-3*Self(n-2): n in [1..37] ]; // Klaus Brockhaus, Dec 03 2009
  • Mathematica
    Join[{1,2,-2}, LinearRecurrence[{-3, -3}, {0, 6}, 25]] (* G. C. Greubel, Jul 27 2016 *)
    LinearRecurrence[{-3,-3},{1,2,-2},40] (* Harvey P. Dale, Jul 21 2024 *)

Formula

a(n) = -3*a(n-1) - 3*a(n-2) for n > 2; a(0) = 1, a(1) = 2, a(2) = -2.
a(n) = 2*A123877(n-1), n>0.
G.f.: 1+2*x*(1+2*x)/(1+3*x+3*x^2).
a(6*m + 3) = 0, m>=0. - G. C. Greubel, Jul 27 2016

Extensions

Edited and extended by Klaus Brockhaus, Dec 03 2009

A199324 Triangle T(n,k), read by rows, given by (-1,1,-1,0,0,0,0,0,0,0,...) DELTA (1,0,0,0,0,0,0,0,0,0,...) where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, -1, 1, 0, -1, 1, 1, -1, -1, 1, -1, 3, -2, -1, 1, 0, -2, 5, -3, -1, 1, 1, -2, -2, 7, -4, -1, 1, -1, 5, -7, -1, 9, -5, -1, 1, 0, -3, 12, -15, 1, 11, -6, -1, 1, 1, -3, -3, 21, -26, 4, 13, -7, -1, 1, -1, 7, -15, 3, 31, -40, 8, 15, -8, -1, 1, 0, -4, 22, -42
Offset: 0

Views

Author

Philippe Deléham, Nov 12 2011

Keywords

Examples

			Triangle begins :
1
-1, 1
0, -1, 1
1, -1, -1, 1
-1, 3, -2, -1, 1
0, -2, 5, -3, -1, 1
1, -2, -2, 7, -4, -1, 1
-1, 5, -7, -1, 9, -5, -1, 1
		

Crossrefs

Cf. A026729, A063967, A129267, A176971 (diagonals sums).

Formula

T(n,k)=T(n-1,k-1)+T(n-2,k-1)-T(n-1,k)-T(n-2,k), T(0,0)=1.
G.f.: 1/(1-(y-1)*x-(y-1)*x^2).
Sum_{k, 0<=k<=n}T(n,k)*x^k = A000748(n), A108520(n), A049347(n), A000007(n), A000045(n+1), A002605(n+1), A030195(n+1), A057087(n), A057088(n), A057089(n), A057090(n), A057091(n), A057092(n), A057093(n) for x = -2,-1,0,1,2,3,4,5,6,7,8,9,10,11 respectively.

A141532 Inverse binomial transform of A141425.

Original entry on oeis.org

1, 1, 1, -2, 4, -8, 7, 22, -125, 376, -878, 1756, -3143, 5188, -8189, 13102, -22928, 45856, -101549, 232618, -524285, 1137148, -2362874, 4725748, -9185771, 17574376, -33554429, 64717378, -127043276, 254086552, -515347553, 1052218462, -2147483645
Offset: 0

Views

Author

Paul Curtz, Aug 12 2008

Keywords

Comments

This is the inverse binomial transform of A141425 if interpreted with offset 0.

Crossrefs

Programs

  • Magma
    I:=[1,1,-2,4,-8]; [1] cat [n le 5 select I[n] else -6*Self(n-1) -15*Self(n-2) -20*Self(n-3) -15*Self(n-4) -6*Self(n-5): n in [1..40]]; // G. C. Greubel, Mar 30 2021
    
  • Mathematica
    LinearRecurrence[{-6,-15,-20,-15,-6}, {1,1,1,-2,4,-8}, 40] (* G. C. Greubel, Mar 30 2021 *)
  • Sage
    def A141532_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (1 +7*x +22*x^2 +39*x^3 +42*x^4 +27*x^5)/((1+x+x^2)*(1+3*x+3*x^2)*(1+2*x)) ).list()
    A141532_list(40) # G. C. Greubel, Mar 30 2021

Formula

G.f.: (1 +7*x +22*x^2 +39*x^3 +42*x^4 +27*x^5)/((1+x+x^2)*(1+3*x+3*x^2)*(1+2*x)). - R. J. Mathar, Nov 11 2008
From G. C. Greubel, Mar 30 2021: (Start)
a(n) = (9/2)*[n=0] + (-2)^(n-1) - (3/2)*( ChebyshevU(n, -1/2) + 2*ChebyshevU(n-1, -1/2) + 3^((n-1)/2)*(sqrt(3)*ChebyshevU(n, -sqrt(3)/2) + 2*ChebyshevU(n-1, -sqrt(3)/2)) ).
a(n) = (9/2)*[n=0] + (-2)^(n-1) - (3/2)*(A049347(n) + 2*A049347(n-1) + A000748(n) + 2*A000748(n-1) ). (End)

Extensions

Extended by R. J. Mathar, Nov 11 2008

A368149 Triangular array T(n,k), read by rows: coefficients of strong divisibility sequence of polynomials p(1,x) = 1, p(2,x) = 1 + 2*x, p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where u = p(2,x), v = 1 - x^2.

Original entry on oeis.org

1, 1, 2, 2, 4, 3, 3, 10, 10, 4, 5, 20, 31, 20, 5, 8, 40, 78, 76, 35, 6, 13, 76, 184, 232, 161, 56, 7, 21, 142, 406, 636, 582, 308, 84, 8, 34, 260, 861, 1604, 1831, 1296, 546, 120, 9, 55, 470, 1766, 3820, 5215, 4630, 2640, 912, 165, 10, 89, 840, 3533, 8696
Offset: 1

Views

Author

Clark Kimberling, Dec 25 2023

Keywords

Comments

Because (p(n,x)) is a strong divisibility sequence, for each integer k, the sequence (p(n,k)) is a strong divisibility sequence of integers.

Examples

			First eight rows:
   1
   1    2
   2    4    3
   3   10   10    4
   5   20   31   20    5
   8   40   78   76   35    6
  13   76  184  232  161   56   7
  21  142  406  636  582  308  84  8
Row 4 represents the polynomial p(4,x) = 3 + 10*x + 10*x^2 + 4*x^3, so (T(4,k)) = (3,10,10,4), k=0..3.
		

Crossrefs

Cf. A000045 (column 1); A000027 (p(n,n-1)); A000244 (row sums), (p(n,1)); A033999 (alternating row sums), (p(n,-1)); A116415 (p(n,2)), A000748, (p(n,-2)); A152268, (p(n,3)); A190969, (p(n,-3)); A094440, A367208, A367209, A367210, A367211, A367297, A367298, A367299, A367300, A367301, A368150.

Programs

  • Mathematica
    p[1, x_] := 1; p[2, x_] := 1 + 2 x; u[x_] := p[2, x]; v[x_] := 1 - x^2;
    p[n_, x_] := Expand[u[x]*p[n - 1, x] + v[x]*p[n - 2, x]]
    Grid[Table[CoefficientList[p[n, x], x], {n, 1, 10}]]
    Flatten[Table[CoefficientList[p[n, x], x], {n, 1, 10}]]

Formula

p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where p(1,x) = 1, p(2,x) = 1 + 2*x, u = p(2,x), and v = 1 - x^2.
p(n,x) = k*(b^n - c^n), where k = -1/sqrt(5 + 4*x), b = (1/2)*(2*x + 1 - 1/k), c = (1/2)*(2*x + 1 + 1/k).

A379825 a(n) = [x^n] x/(12*x^2 - 6*x + 1).

Original entry on oeis.org

0, 1, 6, 24, 72, 144, 0, -1728, -10368, -41472, -124416, -248832, 0, 2985984, 17915904, 71663616, 214990848, 429981696, 0, -5159780352, -30958682112, -123834728448, -371504185344, -743008370688, 0, 8916100448256, 53496602689536, 213986410758144, 641959232274432
Offset: 0

Views

Author

Peter Luschny, Jan 04 2025

Keywords

Crossrefs

Programs

  • Maple
    w := sqrt(-3): a := n -> (w/6)*((3 - w)^n - (3 + w)^n):
    seq(simplify(a(n)), n = 0..28);
    # Alternative:
    a := proc(n) option remember; if n < 2 then n else 6*(a(n - 1) - 2*a(n - 2)) fi end:
    seq(a(n), n = 0..28);
  • Mathematica
    LinearRecurrence[{6,-12},{0,1},29] (* James C. McMahon, Jan 05 2025 *)

Formula

a(n) = n! * [x^n] exp(3*x)*sin(sqrt(3)*x)/sqrt(3).
a(n) = (w/6)*((3 - w)^n - (3 + w)^n) where w = sqrt(-3).
a(n) = 6*a(n - 1) - 12*a(n - 2) for n >= 2.
a(n) = 2^n*3^((n - 1)/2)*sin((Pi*n)/6).
a(n) = 2^(n-1)*A057083(n-1) = 2^(n-1)*3^((n-1)/2)*ChebyshevU(n-1, sqrt(3)/2) for n >= 1.
Previous Showing 11-18 of 18 results.