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 1-5 of 5 results.

A300617 O.g.f. A(x) satisfies: [x^n] exp( n * A(x) ) = n^2 * [x^(n-1)] exp( n * A(x) ) for n>=1.

Original entry on oeis.org

1, 3, 30, 550, 15375, 601398, 31299268, 2093655600, 175312873125, 17987972309725, 2221603804365924, 325310016974127276, 55749742122979646105, 11056914755618659399500, 2513208049272148754203200, 649086459674801585681092992, 189044817293654530855544266209, 61671809408989968268084102641075, 22399957973327602630210233608217250, 9009223131975798265447660437783058050
Offset: 1

Views

Author

Paul D. Hanna, Mar 10 2018

Keywords

Comments

Compare to: [x^n] exp( n * x ) = [x^(n-1)] exp( n * x ) for n>=1.
It is conjectured that this sequence consists entirely of integers.
a(n) is divisible by n*(n+1)/2 (conjecture); A300589(n) = a(n) / (n*(n+1)/2).

Examples

			O.g.f.: A(x) = x + 3*x^2 + 30*x^3 + 550*x^4 + 15375*x^5 + 601398*x^6 + 31299268*x^7 + 2093655600*x^8 + 175312873125*x^9 + 17987972309725*x^10 + ...
where
exp(A(x)) = 1 + x + 7*x^2/2! + 199*x^3/3! + 14065*x^4/4! + 1924201*x^5/5! + 445859911*x^6/6! + 161145717727*x^7/7! + 85790577700129*x^8/8! + ... + A300616(n)*x^n/n! + ...
such that: [x^n] exp( n * A(x) ) = n^2 * [x^(n-1)] exp( n * A(x) ).
RELATED SEQUENCES.
The sequence A300589(n) = a(n) / (n*(n+1)/2) begins:
[1, 1, 5, 55, 1025, 28638, 1117831, 58157100, 3895841625, 327054041995, ...].
The table of coefficients in x^k/k! in exp(-n*A(x)) * (1 - n^2*x) begins:
n=1: [1, 0, 5, 178, 13269, 1853876, 434314705, 158024698350, ...];
n=2: [1, -2, 0, 248, 22976, 3416592, 822150016, 303575549440, ...];
n=3: [1, -6, -27, 0, 21861, 4129758, 1079984097, 415322613324, ...];
n=4: [1, -12, -88, -848, 0, 3286304, 1109402752, 469332346368, ...];
n=5: [1, -20, -195, -2650, -55675, 0, 794678425, 438768342850, ...];
n=6: [1, -30, -360, -5832, -161856, -6828624, 0, 293555007360, ...];
n=7: [1, -42, -595, -10892, -339339, -18549958, -1433676839, 0, ...]; ...
in which the coefficient of x^n in row n forms a diagonal of zeros.
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=[1]); for(i=1, n+1, A=concat(A, 0); V=Vec(Ser(A)^(#A-1)); A[#A] = ((#A-1)^2*V[#A-1] - V[#A])/(#A-1) ); polcoeff( log(Ser(A)), n)}
    for(n=1, 20, print1(a(n), ", "))
    
  • PARI
    {a(n) = my(A=[1]); for(i=1, n, A=concat(A, 0); m=#A; A[m] = -Vec( exp(m^1*x*Ser(A))*(1-m^2*x +x^2*O(x^m))^(1))[m+1]/m ); A[n]}
    for(n=1, 20, print1(a(n), ", "))

Formula

O.g.f. equals the logarithm of the e.g.f. of A300616.
O.g.f. A(x) satisfies: [x^n] exp(-n*A(x)) * (1 - n^2*x) = 0, for n > 0. - Paul D. Hanna, Oct 15 2018
a(n) ~ c * (n!)^2, where c = 1.685041722777551007711429045295022018562828... - Vaclav Kotesovec, Mar 10 2018

A300596 E.g.f. A(x) satisfies: [x^n] A(x)^(n^4) = n^4 * [x^(n-1)] A(x)^(n^4) for n>=1.

Original entry on oeis.org

1, 1, 17, 13171, 56479849, 738706542221, 22885801082965201, 1448479282286023114807, 169382934361790242266135761, 33954915787325983176711221469529, 10997512067125948734754888814957997361, 5482894935903399886164748355296587003210971, 4041251688669102134446309448401146782811371078137
Offset: 0

Views

Author

Paul D. Hanna, Mar 09 2018

Keywords

Comments

Compare e.g.f. to: [x^n] exp(x)^(n^4) = n^3 * [x^(n-1)] exp(x)^(n^4) for n>=1.

Examples

			E.g.f.: A(x) = 1 + x + 17*x^2/2! + 13171*x^3/3! + 56479849*x^4/4! + 738706542221*x^5/5! + 22885801082965201*x^6/6! + 1448479282286023114807*x^7/7! + 169382934361790242266135761*x^8/8! + ...
ILLUSTRATION OF DEFINITION.
The table of coefficients of x^n in A(x)^(n^4) begins:
n=1: [(1), (1), 17/2, 13171/6, 56479849/24, 738706542221/120, ...];
n=2: [1, (16), (256), 113168/3, 114614528/3, 1486010366512/15, ...];
n=3: [1, 81, (7857/2), (636417/2), 1671341283/8, 20586397669407/40, ...];
n=4: [1, 256, 34816, (11641088/3), (2980118528/3), 26464517792512/15, ...];
n=5: [1, 625, 400625/2, 271091875/6, (232095075625/24), (145059422265625/24), ...];
n=6: [1, 1296, 850176, 379068336, 133027474176, (243163666719504/5), (315140112068477184/5), ...]; ...
in which the coefficients in parenthesis are related by
1 = 1*1; 256 = 2^4*16; 636417/2 = 3^4*7857/2; 2980118528/3 = 4^4*11641088/3; ...
illustrating that: [x^n] A(x)^(n^4) = n^4 * [x^(n-1)] A(x)^(n^4).
LOGARITHMIC PROPERTY.
The logarithm of the e.g.f. is the integer series:
log(A(x)) = x + 8*x^2 + 2187*x^3 + 2351104*x^4 + 6153518125*x^5 + 31779658925496*x^6 + 287364845865893467*x^7 + 4200677982722915635200*x^8 + ... + A300597(n)*x^n + ...
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=[1]); for(i=1, n+1, A=concat(A, 0); V=Vec(Ser(A)^((#A-1)^4)); A[#A] = ((#A-1)^4*V[#A-1] - V[#A])/(#A-1)^4 ); n!*A[n+1]}
    for(n=0, 20, print1(a(n), ", "))

Formula

E.g.f. A(x) satisfies: log(A(x)) = Sum_{n>=1} A300597(n)*x^n, a power series in x with integer coefficients.

A300619 O.g.f. A(x) satisfies: [x^n] exp( n * A(x) ) = n^3 * [x^(n-1)] exp( n * A(x) ) for n>=1.

Original entry on oeis.org

1, 7, 207, 14226, 1852800, 409408077, 142286748933, 73448832515952, 53835885818473473, 54041298732304775000, 72129250579997923194091, 124900802377559946754633602, 274851919918333747166200590840, 755158633069275870471471631726803, 2551279948230221759814139760682442500
Offset: 1

Views

Author

Paul D. Hanna, Mar 10 2018

Keywords

Comments

O.g.f. equals the logarithm of the e.g.f. of A300618.
It is remarkable that this sequence should consist entirely of integers.

Examples

			O.g.f.: A(x) = x + 7*x^2 + 207*x^3 + 14226*x^4 + 1852800*x^5 + 409408077*x^6 + 142286748933*x^7 + 73448832515952*x^8 + 53835885818473473*x^9 + ...
where
exp(A(x)) = 1 + x + 15*x^2/2! + 1285*x^3/3! + 347065*x^4/4! + 224232501*x^5/5! + 296201195791*x^6/6! + 719274160258585*x^7/7! + ... + A300618(n)*x^n/n! + ...
such that: [x^n] exp( n * A(x) ) = n^3 * [x^(n-1)] exp( n * A(x) ).
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=[1]); for(i=1, n+1, A=concat(A, 0); V=Vec(Ser(A)^(#A-1)); A[#A] = ((#A-1)^3*V[#A-1] - V[#A])/(#A-1) ); polcoeff( log(Ser(A)), n)}
    for(n=1, 20, print1(a(n), ", "))

A300615 O.g.f. A(x) satisfies: [x^n] exp( n^5 * A(x) ) = n^5 * [x^(n-1)] exp( n^5 * A(x) ) for n>=1.

Original entry on oeis.org

1, 16, 19683, 142475264, 3436799053125, 212148041589128016, 28458158819417861315152, 7380230750280159370894934016, 3385049575573746853297963891959753, 2561548157856026756893458765378989150000, 3026444829408778969259555715061437179090541565, 5340113530831632053993990154143996936096662034267136
Offset: 1

Views

Author

Paul D. Hanna, Mar 10 2018

Keywords

Comments

Compare to: [x^n] exp( n^5 * x ) = n^4 * [x^(n-1)] exp( n^5 * x ) for n>=1.

Examples

			O.g.f.: A(x) = x + 16*x^2 + 19683*x^3 + 142475264*x^4 + 3436799053125*x^5 + 212148041589128016*x^6 + 28458158819417861315152*x^7 + ...
where
exp(A(x)) = 1 + x + 33*x^2/2! + 118195*x^3/3! + 3419881993*x^4/4! + 412433022394701*x^5/5! + 152749066271797582081*x^6/6! + ... + A300614(n)*x^n/n! + ...
such that: [x^n] exp( n^5 * A(x) ) = n^5 * [x^(n-1)] exp( n^5 * A(x) ).
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=[1]); for(i=1, n+1, A=concat(A, 0); V=Vec(Ser(A)^((#A-1)^5)); A[#A] = ((#A-1)^5*V[#A-1] - V[#A])/(#A-1)^5 ); polcoeff( log(Ser(A)), n)}
    for(n=1, 20, print1(a(n), ", "))

Formula

O.g.f. equals the logarithm of the e.g.f. of A300614.

A300625 Table of row functions R(n,x) that satisfy: [x^k] exp( k^n * R(n,x) ) = k^n * [x^(k-1)] exp( k^n * R(n,x) ) for k>=1, n>=1, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 1, 4, 27, 14, 1, 8, 243, 736, 85, 1, 16, 2187, 40448, 30525, 621, 1, 32, 19683, 2351104, 12519125, 1715454, 5236, 1, 64, 177147, 142475264, 6153518125, 6111917748, 123198985, 49680, 1, 128, 1594323, 8856272896, 3436799053125, 31779658925496, 4308276119854, 10931897664, 521721, 1, 256, 14348907, 558312194048, 2049047412828125, 212148041589128016, 287364845865893467, 4151360558858752, 1172808994833, 5994155
Offset: 1

Views

Author

Paul D. Hanna, Mar 12 2018

Keywords

Examples

			This table of coefficients T(n,k) begins:
n=1: [1, 1, 3, 14, 85, 621, 5236, 49680, ...];
n=2: [1, 2, 27, 736, 30525, 1715454, 123198985, 10931897664, ...];
n=3: [1, 4, 243, 40448, 12519125, 6111917748, 4308276119854, ..];
n=4: [1, 8, 2187, 2351104, 6153518125, 31779658925496, ...];
n=5: [1, 16, 19683, 142475264, 3436799053125, 212148041589128016, ...];
n=6: [1, 32, 177147, 8856272896, 2049047412828125, 1569837215111038900704, ...];
n=7: [1, 64, 1594323, 558312194048, 1256793474918203125, 12020665333382306853887808, ...]; ...
such that row functions R(n,x) = Sum_{k>=1} T(n,k)*x^k satisfy:
[x^k] exp( k^n * R(n,x) ) = k^n * [x^(k-1)] exp( k^n * R(n,x) ) for k>=1.
Row functions R(n,x) begin:
R(1,x) = x + x^2 + 3*x^3 + 14*x^4 + 85*x^5 + 621*x^6 + 5236*x^7 + 49680*x^8 + ...
R(2,x) = x + 2*x^2 + 27*x^3 + 736*x^4 + 30525*x^5 + 1715454*x^6 + ...
R(3,x) = x + 4*x^2 + 243*x^3 + 40448*x^4 + 12519125*x^5 + 6111917748*x^6 + ...
R(4,x) = x + 8*x^2 + 2187*x^3 + 2351104*x^4 + 6153518125*x^5 + ...
etc.
		

Crossrefs

Cf. A088716 (row 1), A300591 (row 2), A300595 (row 3), A300597 (row 4).

Programs

  • PARI
    {T(n, k) = my(A=[1]); for(i=1, k+1, A=concat(A, 0); V=Vec(Ser(A)^((#A-1)^n)); A[#A] = ((#A-1)^n * V[#A-1] - V[#A])/(#A-1)^n ); polcoeff( log(Ser(A)), k)}
    /* Print as a table of row functions: */
    for(n=1, 8, for(k=1, 8, print1(T(n, k), ", ")); print(""))
    /* Print as a flattened triangle: */
    for(n=1, 12, for(k=1, n-1, print1(T(n-k, k), ", ")); )
Showing 1-5 of 5 results.