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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A251686 G.f.: exp( Sum_{n>=1} A132303(n)/3 * x^n/n ), where A132303(n) = sum of the cubes of the trinomial coefficients in row n of triangle A027907.

Original entry on oeis.org

1, 1, 8, 100, 1556, 27260, 515510, 10284094, 213433728, 4566363088, 100082133066, 2236952393302, 50817223209451, 1170319824912699, 27268900054818390, 641812268110993694, 15239341125950643462, 364655982858022960206, 8785745372509009963892, 212976842702489760621536
Offset: 0

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Author

Paul D. Hanna, Feb 28 2015

Keywords

Comments

Self-convolution cube yields A168593.

Examples

			G.f.: A(x) = 1 + x + 8*x^2 + 100*x^3 + 1556*x^4 + 27260*x^5 +...
where
log(A(x)) = 1*x + 15*x^2/2 + 277*x^3/3 + 5727*x^4/4 + 125301*x^5/5 + 2843643*x^6/6 + 66214485*x^7/7 + 1571497119*x^8/8 +...+ A132303(n)/3*x^n/n +...
		

Crossrefs

Programs

  • PARI
    {A027907(n,k) = polcoeff((1+x+x^2)^n, k)}
    {A132303(n) = sum(k=0, 2*n, A027907(n,k)^3)}
    {a(n) = if(n==0, 1, polcoeff(exp(sum(m=1, n, A132303(m)/3 * x^m/m) +x*O(x^n)), n))}
    for(n=0,30,print1(a(n),", "))

A027909 T(2n,n-1), T given by A027907.

Original entry on oeis.org

1, 4, 21, 112, 615, 3432, 19383, 110448, 633726, 3656360, 21191555, 123286440, 719539015, 4210967880, 24702429825, 145210795200, 855172338570, 5044470461352, 29799593861974, 176268499363840, 1043889366927771, 6188748520285584, 36726461258947569, 218146172715259488, 1296812014083995850
Offset: 0

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Author

Keywords

Programs

  • Maple
    seq(add(binomial(j,2*j-3*n-4)*binomial(2*n+2,j),j=0...2*n+2),n=0..25);  # Mark van Hoeij, May 12 2013
  • PARI
    a(n)=sum(j=0,2*n+2,binomial(j, 2*j-3*n-4)*binomial(2*n+2, j)); \\ Joerg Arndt, May 13 2013~

Formula

G.f.: -g*(g^2+g+1)/(3*g^2+g-1) where g = x times the g.f. of A143927. - Mark van Hoeij, Nov 16 2011

Extensions

Corrected offset, more terms, Joerg Arndt, May 13 2013

A027911 a(n) = T(2*n+1,n), with T given by A027907.

Original entry on oeis.org

1, 3, 15, 77, 414, 2277, 12727, 71955, 410346, 2355962, 13599915, 78855339, 458917850, 2679183405, 15683407785, 92022516525, 541050073146, 3186886397310, 18801598011274, 111083331666918, 657153430251396, 3892199032434105, 23077435617920925, 136963282273730613, 813597690808666386
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Maple
    seq(add(binomial(j,2*j-2-3*n)*binomial(2*n+1,j),j=0...2*n+1),n=0..20);  # Mark van Hoeij, May 12 2013
  • Mathematica
    Table[GegenbauerC[n, -2 n - 1, -1/2], {n, 0, 100}] (* Emanuele Munarini, Oct 20 2016 *)
  • Maxima
    makelist(ultraspherical(n,-2*n-1,-1/2),n,0,12); /* Emanuele Munarini, Oct 20 2016 */
    
  • PARI
    a(n)=sum(j=0, 2*n+1, binomial(j, 2*j-2-3*n)*binomial(2*n+1, j)); \\ Joerg Arndt, Oct 20 2016

Formula

a(n) = GegenbauerPoly(n,-2*n-1,-1/2). - Emanuele Munarini, Oct 20 2016
G.f.: g/(1-g-3*g^2), where g = x times the g.f. of A143927. - Mark van Hoeij, Nov 16 2011
a(n) = Sum_{k=0..floor(n/2)} binomial(2*n+1,k)*binomial(2*n+1-k,n-2*k). - Emanuele Munarini, Oct 20 2016

Extensions

More terms from Joerg Arndt, Oct 20 2016

A027912 T(2n-1,n-2), T given by A027907.

Original entry on oeis.org

1, 5, 28, 156, 880, 5005, 28665, 165104, 955434, 5550755, 32355917, 189147400, 1108476720, 6510243495, 38308997100, 225810489168, 1333057076890
Offset: 2

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Author

Keywords

A059781 Triangle T(n,k) giving exponent of power of 2 dividing entry (n,k) of trinomial triangle A027907.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 2, 1, 4, 0, 4, 1, 2, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 0, 2, 0, 0, 1, 0, 0, 0, 1, 0, 0, 2, 0, 0, 0, 3, 2, 4, 1, 3, 4, 3, 0, 3, 4, 3, 1, 4, 2, 3, 0, 0, 0, 0, 2, 1, 1, 1, 8, 0, 0, 0, 8, 1, 1, 1, 2, 0, 0, 0, 0, 1, 0, 1, 0
Offset: 0

Views

Author

N. J. A. Sloane, Feb 22 2001

Keywords

Examples

			0; 0,0,0; 0,1,0,1,0; ...
		

References

  • Boris A. Bondarenko, Generalized Pascal Triangles and Pyramids (in Russian), FAN, Tashkent, 1990, ISBN 5-648-00738-8.

Programs

  • Maple
    with(numtheory): T := proc(i,j) option remember: if i >= 0 and j=0 then RETURN(1) fi: if i >= 0 and j=2*i then RETURN(1) fi: if i >= 1 and j=1 then RETURN(i) fi: if i >= 1 and j=2*i-1 then RETURN(i) fi: T(i-1,j-2)+T(i-1,j-1)+T(i-1,j): end: for i from 0 to 20 do for j from 0 to 2*i do if T(i,j) mod 2 = 1 then printf(`%d,`,0) else printf(`%d,`, ifactors(T(i,j))[2,1,2] ) fi: od:od: # James Sellers, Feb 22 2001

Extensions

More terms from James Sellers, Feb 22 2001

A059782 Triangle T(n,k) giving exponent of power of 3 dividing entry (n,k) of trinomial triangle A027907.

Original entry on oeis.org

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

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Author

N. J. A. Sloane, Feb 22 2001

Keywords

Examples

			0; 0,0,0; 0,0,1,0,0; 0,1,1,0,1,1,0; ...
		

References

  • Boris A. Bondarenko, Generalized Pascal Triangles and Pyramids (in Russian), FAN, Tashkent, 1990, ISBN 5-648-00738-8.

Programs

  • Maple
    with(numtheory): T := proc(i,j) option remember: if i >= 0 and j=0 then RETURN(1) fi: if i >= 0 and j=2*i then RETURN(1) fi: if i >= 1 and j=1 then RETURN(i) fi: if i >= 1 and j=2*i-1 then RETURN(i) fi: T(i-1,j-2)+T(i-1,j-1)+T(i-1,j): end: for i from 0 to 20 do for j from 0 to 2*i do if T(i,j) mod 3 <> 0 then printf(`%d,`,0) fi: if T(i,j) mod 3 = 0 and T(i,j) mod 2 = 0 then printf(`%d,`, ifactors(T(i,j))[2,2,2] ) fi: if T(i,j) mod 3 = 0 and T(i,j) mod 2 = 1 then printf(`%d,`, ifactors(T(i,j))[2,1,2] ) fi: #printf(`%d,`,T(i,j)) od:od: # James Sellers, Feb 22 2001

Extensions

More terms from James Sellers, Feb 22 2001

A101617 The trinomial transform (A027907) gives powers of 3, while the trinomial transform of this sequence shift one place left gives powers of 5.

Original entry on oeis.org

1, 1, 1, 3, -3, 19, -43, 139, -355, 995, -2587, 6907, -17939, 46931, -121419, 314603, -811203, 2091459, -5379963, 13833179, -35527795, 91210035, -234020267, 600258507, -1539135779, 3945762211, -10113490139, 25918908603, -66417608403, 170182721299, -436032111883, 1117120911019
Offset: 0

Views

Author

Paul D. Hanna, Dec 09 2004

Keywords

Examples

			3^3 = 1*(1) + 3*(1) + 6*(1) + 7*(3) + 6*(-3) + 3*(19) + 1*(-43).
5^3 = 1*(1) + 3*(1) + 6*(3) + 7*(-3) + 6*(19) + 3*(-43) + 1*(139).
In general, a sequence A with the property that the
trinomial transform of A gives powers of P, while the
trinomial transform of LSHIFT(A) gives powers of Q
has the g.f.: N(x)/D(x) where
N(x)=(1+3*x-(Q-3)*x^2-(P+Q-2)*x^3) and
D(x)=(1+2*x-(P+Q-3)*x^2-(P+Q-2)*x^3+(P-1)*(Q-1)*x^4).
		

Crossrefs

Programs

  • Mathematica
    nn:=31; CoefficientList[Series[(1 + 3*x - 2*x^2 - 6*x^3)/(1 + 2*x - 5*x
    ^2 - 6*x^3 + 8*x^4),{x,0,nn}],x] (* Georg Fischer, Apr 17 2020 *)
  • PARI
    {a(n)=local(P=3,Q=5,V=[1,1]);if(n>1, for(m=1,n, V=concat(V,P^m-sum(k=0,2*m-1,polcoeff((1+x+x^2)^m+x*O(x^k),k)*V[k+1])); V=concat(V,Q^m-sum(k=0,2*m-1,polcoeff((1+x+x^2)^m+x*O(x^k),k)*V[k+2])); ));V[n+1]}
    for(n=0,30,print1(a(n),", "))

Formula

G.f.: A(x) = (1 + 3*x - 2*x^2 - 6*x^3)/(1 + 2*x - 5*x^2 - 6*x^3 + 8*x^4). [corrected by Georg Fischer, Apr 17 2020]
3^n = Sum_{k=0..2*n} A027907(n, k)*a(k) for n>=0 and
5^n = Sum_{k=0..2*n} A027907(n, k)*a(k+1) for n>=0.
a(n) = (-1)^n*A006131(n-1) + (1/3)[(-2)^n + 2]. - Ralf Stephan, May 16 2007

A123934 Triangle T(n,k), 1<=k<=n :forms the odd-indexed trinomial coefficients (A027907).

Original entry on oeis.org

1, 2, 2, 3, 7, 3, 4, 16, 16, 4, 5, 30, 51, 30, 5, 6, 50, 126, 126, 50, 6, 7, 77, 266, 393, 266, 77, 7
Offset: 1

Views

Author

Philippe Deléham, Oct 30 2006

Keywords

Examples

			Triangle begins:
1;
2, 2;
3, 7, 3;
4, 16, 16, 4;
5, 30, 51, 30, 5;
6, 50, 126, 126, 50, 6;
7, 77, 266, 393, 266, 77, 7;
		

Crossrefs

Cf. A056241.

Formula

Sum_{k, 1<=k<=n}T(n,k)=A003462(n)=(3^n-1)/2.

A136168 a(n) = (n-1)!*Sum_{i=1..n-1} (-1)^(i+1)*A027907(n-i+2,i+1)*a(n-i)/(n-i)! for n>0 with a(0)=1, where A027907 is the triangle of trinomial coefficients.

Original entry on oeis.org

1, 3, 16, 120, 1140, 12972, 171216, 2571912, 43429680, 816108048, 16894168704, 381536713152, 9332214825024, 246215663789760, 6984603724315392, 211834855804295808, 6819603388970206464, 232454553855108173568
Offset: 0

Views

Author

Paul D. Hanna, Dec 27 2007, Jan 24 2008

Keywords

Examples

			E.g.f.: A(x) = 1 + 3x + 16x^2/2! + 120x^3/3! + 1140x^4/4! + 12972x^5/5! +...
		

Crossrefs

Cf. A027907; A005119 (variant).

Programs

  • PARI
    {a(n)=if(n<0,0,if(n==0,1,(n-1)!*sum(i=1,n,(-1)^(i+1)*polcoeff((1+x+x^2)^(n-i+2),i+1)*a(n-i)/(n-i)!)))}

Formula

E.g.f. satisfies: A(x) = (1-x+x^2)^2/(1-2x)*A(x-x^2+x^3).

A145171 Triangle read by rows: left half of trinomial triangle (A027907) modulo 3.

Original entry on oeis.org

1, 1, 1, 1, 2, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 0, 0, 0, 0, 1, 0, 0, 2, 0, 0, 0, 1, 1, 1, 2, 2, 2, 0, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1
Offset: 1

Views

Author

Reikku Kulon, Oct 03 2008

Keywords

Crossrefs

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