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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A220353 G.f.: Sum_{n>=0} (1 - (1-x)^n)^n.

Original entry on oeis.org

1, 1, 4, 23, 176, 1697, 19805, 271669, 4285195, 76430799, 1521161530, 33422603485, 803584699252, 20986514811397, 591616582807036, 17905570068475471, 579092313210791549, 19931241131544637637, 727395001560116046739, 28057672464546863483509, 1140566596105346550309751, 48735378037084078566334897, 2183719157723179429519093520, 102386962560815561519635957007
Offset: 0

Views

Author

Paul D. Hanna, Dec 11 2012

Keywords

Comments

Limit n->infinity A220353(n)/A187826(n) = 1. - Vaclav Kotesovec, Nov 08 2014

Examples

			G.f.: A(x) = 1 + x + 4*x^2 + 23*x^3 + 176*x^4 + 1697*x^5 + 19805*x^6 +...
where the g.f. satisfies the identities:
(1) A(x) = 1 + x + (2*x - x^2)^2 + (3*x - 3*x^2 + x^3)^3 + (4*x - 6*x^2 + 4*x^3 - x^4)^4 + (5*x - 10*x^2 + 10*x^3 - 5*x^4 + x^5)^5 +...
(2) A(x) = (1-x) + (1-x)^2*(2*x - x^2) + (1-x)^3*(3*x - 3*x^2 + x^3)^2 + (1-x)^4*(4*x - 6*x^2 + 4*x^3 - x^4)^3 + (1-x)^5*(5*x - 10*x^2 + 10*x^3 - 5*x^4 + x^5)^4 +...
		

Crossrefs

Programs

  • Mathematica
    terms = 24;
    gf = 1 + Sum[(1 - (1 - x)^n)^n, {n, 1, terms}] + O[x]^terms;
    CoefficientList[gf, x] (* Jean-François Alcover, Jul 01 2018 *)
  • PARI
    {a(n)=local(q=1/(1-x+x*O(x^n)),A=1);A=sum(k=0,n,q^(-k^2)*(q^k-1)^k);polcoeff(A,n)}
    for(n=0,30,print1(a(n),", "))
    
  • PARI
    {a(n)=local(q=1/(1-x+x*O(x^n)),A=1);A=sum(k=1,n+1,q^(-k^2)*(q^k-1)^(k-1));polcoeff(A,n)}
    for(n=0,30,print1(a(n),", "))

Formula

G.f.: Sum_{n>=1} (1-x)^n * (1 - (1-x)^n)^(n-1).
a(n) = c * n! / (sqrt(n) * (log(2))^(2*n)), where c = 0.93418651575946259471737... . - Vaclav Kotesovec, May 06 2014
In closed form, c = 2^(log(2)/2-1) / (log(2) * sqrt(Pi*(1-log(2)))). - Vaclav Kotesovec, May 03 2015

Extensions

a(22)-a(23) corrected by Andrew Howroyd, Feb 22 2018

A301584 G.f.: Sum_{n>=0} ((1+x)^(2*n) - 1)^n.

Original entry on oeis.org

1, 2, 17, 264, 5784, 163610, 5667551, 232280480, 10991951114, 589780778314, 35379149504709, 2346218124687516, 170439977706143335, 13459938431949414118, 1148107512505151099653, 105194122765096703619248, 10303686044959088279454117, 1074408525677705370497704526, 118828297870115694372235974855, 13893778686151373846512389392672, 1712370237144948501135060958863978
Offset: 0

Views

Author

Paul D. Hanna, Mar 24 2018

Keywords

Examples

			G.f.: A(x) = 1 + 2*x + 17*x^2 + 264*x^3 + 5784*x^4 + 163610*x^5 + 5667551*x^6 + 232280480*x^7 + 10991951114*x^8 + 589780778314*x^9 + ...
such that
A(x) = 1 + ((1+x)^2-1) + ((1+x)^4-1)^2 + ((1+x)^6-1)^3 + ((1+x)^8-1)^4 + ((1+x)^10-1)^5 + ((1+x)^12-1)^6 + ((1+x)^14-1)^7 + ...
Also,
A(x) = 1/2 + (1+x)^2/(1 + (1+x)^2)^2 + (1+x)^8/(1 + (1+x)^4)^3 + (1+x)^18/(1 + (1+x)^6)^4 + (1+x)^32/(1 + (1+x)^8)^5 + (1+x)^50/(1 + (1+x)^10)^6 + ...
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A,o=x*O(x^n)); A = sum(m=0,n, ((1+x +o)^(2*m) - 1)^m ); polcoeff(A,n)}
    for(n=0,30,print1(a(n),", "))

Formula

G.f.: Sum_{n>=0} (1+x)^(2*n^2) /(1 + (1+x)^(2*n))^(n+1).
a(n) ~ c * d^n * n! / sqrt(n), where d = 2*A317855 = 6.3221773077308576276603444051762649834527655483771126832545564150753941184386... and c = 0.302715376391132275494451399946850989516917... - Vaclav Kotesovec, Aug 09 2018

A302615 G.f.: Sum_{n>=0} (3 + (1+x)^n)^n / (4 + (1+x)^n)^(n+1).

Original entry on oeis.org

1, 1, 10, 130, 2390, 56714, 1644138, 56327820, 2226708772, 99761490536, 4995375316146, 276464859358474, 16757956600528786, 1104116777798713154, 78565751676021256606, 6004629888868350015506, 490572645247461234631946, 42665124626946741636482996, 3935474733572880332326074450, 383756013888633346483785849474
Offset: 0

Views

Author

Paul D. Hanna, Apr 10 2018

Keywords

Comments

The following identity holds for |y| <= 1 and fixed real k > 0:
Sum_{n>=0} (k + y^n)^n/(1+k + y^n)^(n+1) = Sum_{n>=0} (y^n - 1)^n/(1+k - k*y^n)^(n+1).

Examples

			G.f.: A(x) = 1 + x + 10*x^2 + 130*x^3 + 2390*x^4 + 56714*x^5 + 1644138*x^6 + 56327820*x^7 + 2226708772*x^8 + 99761490536*x^9 + ...
such that
A(x) = 1/5  +  (3 + (1+x))/(4 + (1+x))^2  +  (3 + (1+x)^2)^2/(4 + (1+x)^2)^3  +  (3 + (1+x)^3)^3/(4 + (1+x)^3)^4  +  (3 + (1+x)^4)^4/(4 + (1+x)^4)^5  +  (3 + (1+x)^5)^5/(4 + (1+x)^5)^6  +  (3 + (1+x)^6)^6/(4 + (1+x)^6)^7  + ...
Also,
A(x) = 1  +  ((1+x) - 1)/(4 - 3*(1+x))^2  +  ((1+x)^2 - 1)^2/(4 - 3*(1+x)^2)^3  +  ((1+x)^3 - 1)^3/(4 - 3*(1+x)^3)^4  +  ((1+x)^4 - 1)^4/(4 - 3*(1+x)^4)^5  +  ((1+x)^5 - 1)^5/(4 - 3*(1+x)^5)^6  +  ((1+x)^6 - 1)^6/(4 - 3*(1+x)^6)^7 + ...
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=1, o=x*O(x^n)); A = sum(m=0, n, ((1+x +o)^m - 1)^m / (4 - 3*(1+x +o)^m)^(m+1)); polcoeff(A, n)}
    for(n=0, 30, print1(a(n), ", "))

Formula

G.f.: Sum_{n>=0} ((1+x)^n - 1)^n / (4 - 3*(1+x)^n)^(n+1).
a(n) ~ c * d^n * n! / sqrt(n), where d = 5.2709551504518355656831902094014170087... and c = 0.26621450180820822374221893929... - Vaclav Kotesovec, Aug 09 2018

A122419 Number of labeled digraphs with n arcs and with no vertex of indegree 0.

Original entry on oeis.org

1, 0, 1, 8, 93, 1354, 23900, 496244, 11855700, 320428318, 9667220397, 322072882348, 11744421711587, 465270864839688, 19899234175413257, 913836170567749048, 44849438199960187278, 2342666125012348876152
Offset: 0

Views

Author

Vladeta Jovovic, Sep 03 2006

Keywords

Crossrefs

Programs

  • Maple
    A122418 := proc(n) option remember ; add( combinat[stirling2](n,k)*(k-1)^n*k!,k=0..n) ; end: A122419 := proc(n) option remember ; add( combinat[stirling1](n,k)*A122418(k),k=0..n)/n! ; end: for n from 0 to 30 do printf("%d, ",A122419(n)) ; od ; # R. J. Mathar, May 18 2007
  • Mathematica
    nmax=20; CoefficientList[Series[Sum[((1+x)^(n-1)-1)^n, {n, 0, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, May 06 2014 *)

Formula

a(n) = (1/n!)*Sum_{k=0..n} Stirling1(n,k)*A122418(k).
G.f.: Sum_{n>=0} ((1+x)^(n-1) - 1)^n.
a(n) ~ c * d^n * n! / sqrt(n), where d = A317855 = (1+exp(1/r))*r^2 = 3.161088653865428813830172202588132491726382774188556341627278..., r = 0.8737024332396683304965683047207192982139922672025395099... is the root of the equation exp(1/r)/r + (1+exp(1/r))*LambertW(-exp(-1/r)/r) = 0, and c = 0.08904589343883135100956914504938... . - Vaclav Kotesovec, May 07 2014

Extensions

More terms from R. J. Mathar, May 18 2007

A301585 G.f.: Sum_{n>=0} ((1+x)^(3*n) - 1)^n.

Original entry on oeis.org

1, 3, 39, 910, 29949, 1271751, 66116065, 4066082856, 288701376912, 23240635243591, 2091554595246705, 208085119389952134, 22676957610808295192, 2686515300821612112411, 343760257348413122290260, 47248346582443326267328400, 6942339982115290619799947901, 1085919469129099832397573088863, 180160797497273341662653292624309, 31598815412054398239059538582525618
Offset: 0

Views

Author

Paul D. Hanna, Mar 24 2018

Keywords

Examples

			G.f.: A(x) = 1 + 3*x + 39*x^2 + 910*x^3 + 29949*x^4 + 1271751*x^5 + 66116065*x^6 + 4066082856*x^7 + 288701376912*x^8 + ...
such that
A(x) = 1 + ((1+x)^3-1) + ((1+x)^6-1)^2 + ((1+x)^9-1)^3 + ((1+x)^12-1)^4 + ((1+x)^15-1)^5 + ((1+x)^18-1)^6 + ((1+x)^21-1)^7 + ...
Also,
A(x) = 1/2 + (1+x)^3/(1 + (1+x)^3)^2 + (1+x)^12/(1 + (1+x)^6)^3 + (1+x)^27/(1 + (1+x)^9)^4 + (1+x)^48/(1 + (1+x)^12)^5 + (1+x)^75/(1 + (1+x)^15)^6 + ...
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A,o=x*O(x^n)); A = sum(m=0,n, ((1+x +o)^(3*m) - 1)^m ); polcoeff(A,n)}
    for(n=0,30,print1(a(n),", "))

Formula

G.f.: Sum_{n>=0} (1+x)^(3*n^2) /(1 + (1+x)^(3*n))^(n+1).
a(n) ~ c * d^n * n! / sqrt(n), where d = 3*A317855 = 9.4832659615962864414905166077643974751791483225656690248818346226130911776579... and c = 0.3108017465925995208675813879173750641359609... - Vaclav Kotesovec, Aug 09 2018

A301586 G.f.: Sum_{n>=0} ((1+x)^(4*n) - 1)^n.

Original entry on oeis.org

1, 4, 70, 2180, 95729, 5422192, 375951144, 30833206304, 2919367902648, 313380517364324, 37606931999739230, 4988933437333555060, 724960700435104219679, 114519163835687116024256, 19538926882901715534673728, 3580844611314789257667535968, 701546780854024941112271649610, 146318317830136401429653726419700, 32367591848747955557013839920695374, 7569528177000020896435962191564396740
Offset: 0

Views

Author

Paul D. Hanna, Mar 24 2018

Keywords

Examples

			G.f.: A(x) = 1 + 4*x + 70*x^2 + 2180*x^3 + 95729*x^4 + 5422192*x^5 + 375951144*x^6 + 30833206304*x^7 + ...
such that
A(x) = 1 + ((1+x)^4-1) + ((1+x)^8-1)^2 + ((1+x)^12-1)^3 + ((1+x)^16-1)^4 + ((1+x)^20-1)^5 + ((1+x)^24-1)^6 + ((1+x)^28-1)^7 + ...
Also,
A(x) = 1/2 + (1+x)^4/(1 + (1+x)^4)^2 + (1+x)^16/(1 + (1+x)^8)^3 + (1+x)^36/(1 + (1+x)^12)^4 + (1+x)^64/(1 + (1+x)^16)^5 + (1+x)^100/(1 + (1+x)^20)^6 + ...
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A,o=x*O(x^n)); A = sum(m=0,n, ((1+x +o)^(4*m) - 1)^m ); polcoeff(A,n)}
    for(n=0,30,print1(a(n),", "))

Formula

G.f.: Sum_{n>=0} (1+x)^(4*n^2) /(1 + (1+x)^(4*n))^(n+1).
a(n) ~ c * d^n * n! / sqrt(n), where d = 4*A317855 = 12.64435461546171525532068881035252996690553109675422536650911283015078823687... and c = 0.31492557816516652573983016205911709623053... - Vaclav Kotesovec, Aug 09 2018

A302614 G.f.: Sum_{n>=0} (2 + (1+x)^n)^n / (3 + (1+x)^n)^(n+1).

Original entry on oeis.org

1, 1, 8, 91, 1474, 30765, 785053, 23682833, 824522797, 32537599175, 1435199414014, 69973425937141, 3736662443907962, 216901789032691605, 13598124265965160130, 915670842666691879191, 65913110467411283181409, 5050836914009172555862713, 410501468976427335127369669, 35269929119728622895198302033, 3194195105084750546987502710855
Offset: 0

Views

Author

Paul D. Hanna, Apr 10 2018

Keywords

Comments

The following identity holds for |y| <= 1 and fixed real k > 0:
Sum_{n>=0} (k + y^n)^n/(1+k + y^n)^(n+1) = Sum_{n>=0} (y^n - 1)^n/(1+k - k*y^n)^(n+1).

Examples

			G.f.: A(x) = 1 + x + 8*x^2 + 91*x^3 + 1474*x^4 + 30765*x^5 + 785053*x^6 + 23682833*x^7 + 824522797*x^8 + 32537599175*x^9 + ...
such that
A(x) = 1/4  +  (2 + (1+x))/(3 + (1+x))^2  +  (2 + (1+x)^2)^2/(3 + (1+x)^2)^3  +  (2 + (1+x)^3)^3/(3 + (1+x)^3)^4  +  (2 + (1+x)^4)^4/(3 + (1+x)^4)^5  +  (2 + (1+x)^5)^5/(3 + (1+x)^5)^6  +  (2 + (1+x)^6)^6/(3 + (1+x)^6)^7  + ...
Also,
A(x) = 1  +  ((1+x) - 1)/(3 - 2*(1+x))^2  +  ((1+x)^2 - 1)^2/(3 - 2*(1+x)^2)^3  +  ((1+x)^3 - 1)^3/(3 - 2*(1+x)^3)^4  +  ((1+x)^4 - 1)^4/(3 - 2*(1+x)^4)^5  +  ((1+x)^5 - 1)^5/(3 - 2*(1+x)^5)^6  +  ((1+x)^6 - 1)^6/(3 - 2*(1+x)^6)^7 + ...
RELATED INFINITE SERIES.
(1) At x = -1/3: the following sums are equal
S1 = Sum_{n>=0} 3^n * (2*3^n + 2^n)^n / (3^(n+1) + 2^n)^(n+1),
S1 = Sum_{n>=0} (-3)^n * (3^n - 2^n)^n / (3^(n+1) - 2^(n+1))^(n+1).
Explicitly,
S1 = 1/4 + 3*8/11^2 + 9*22^2/31^3 + 27*62^3/89^4 + 81*178^4/259^5 + 243*518^5/761^6 + 729*1522^6/2251^7 + 2187*4502^7/6689^8 + 6561*13378^8/19939^9 + 19683*39878^9/59561^10 + ...
S1 = 1 - 3*1/5^2 + 9*5^2/19^3 - 27*19^3/65^4 + 81*65^4/211^5 - 243*211^5/665^6 + 729*665^6/2059^7 - 2187*2059^7/6305^8 + 6561*6305^8/19171^9 - 19683*19171^9/58025^10 + ...
where S1 = 0.90501051059439877583104471171480036033530856741889530664913...
(2) At x = -1/2: the following sums are equal
S2 = Sum_{n>=0} 2^n * (2^(n+1) + 1)^n / (3*2^n + 1)^(n+1),
S2 = Sum_{n>=0} (-2)^n * (2^n - 1)^n / (3*2^n - 2)^(n+1).
Explicitly,
S2 = 1/4 + 2*5/7^2 + 4*9^2/13^3 + 8*17^3/25^4 + 16*33^4/49^5 + 32*65^5/97^6 + 64*129^6/193^7 + 128*257^7/385^8 + 256*513^8/769^9 + 512*1025^9/1537^10 + ...
S2 = 1 - 2*1/4^2 + 4*3^2/10^3 - 8*7^3/22^4 + 16*15^4/46^5 - 32*31^5/94^6 + 64*63^6/190^7 - 128*127^7/382^8 + 256*255^8/766^9 - 512*511^9/1534^10 + ...
where S2 = 0.90222608896798122564942421232120719521782835530371831680447...
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=1, o=x*O(x^n)); A = sum(m=0, n, ((1+x +o)^m - 1)^m / (3 - 2*(1+x +o)^m)^(m+1)); polcoeff(A, n)}
    for(n=0, 30, print1(a(n), ", "))

Formula

G.f.: Sum_{n>=0} ((1+x)^n - 1)^n / (3 - 2*(1+x)^n)^(n+1).
a(n) ~ c * d^n * n! / sqrt(n), where d = 4.64471605501103711823541367464... and c = 0.270134222044915506270113032... - Vaclav Kotesovec, Aug 10 2018

A227619 G.f.: A(x) = 1+x + Sum_{n>=2} (A(x)^n - 1)^n.

Original entry on oeis.org

1, 1, 4, 63, 1278, 29764, 758065, 20611793, 590579518, 17707907024, 553879330720, 18066513887790, 615744470668778, 22014659625607877, 830262409494773896, 33243718957578687811, 1422095813097928147636, 65311403344808947050730, 3227884786251446164710376
Offset: 0

Views

Author

Paul D. Hanna, Aug 21 2013

Keywords

Examples

			G.f.: A(x) = 1 + x + 4*x^2 + 63*x^3 + 1278*x^4 + 29764*x^5 +...
where
A(x) = 1+x + (A(x)^2 - 1)^2 + (A(x)^3 - 1)^3 + (A(x)^4 - 1)^4 + (A(x)^5 - 1)^5 +...
		

Crossrefs

Cf. A122400.

Programs

  • PARI
    {a(n)=local(A=1+x);for(i=1,n,A=1+x+sum(k=2,n,(A^k-1 +x*O(x^n))^k));polcoeff(A,n)}
    for(n=0,20,print1(a(n),", "))

Formula

a(n) ~ c * d^n * n! / sqrt(n), where d = A317855 = (1+exp(1/r))*r^2 = 3.161088653865428813830172202588132491726382774188556341627278..., r = 0.8737024332396683304965683047207192982139922672025395099... is the root of the equation exp(1/r)/r + (1+exp(1/r))*LambertW(-exp(-1/r)/r) = 0, and c = 0.9913753087... . - Vaclav Kotesovec, May 07 2014

A232192 G.f. satisfies: A(x) = 1 + x*Sum_{n>=0} (A(x)^n - 1)^n.

Original entry on oeis.org

1, 1, 1, 5, 44, 519, 7590, 132347, 2689046, 62644234, 1651650774, 48731341965, 1592908456996, 57173688136781, 2235773294509565, 94608603077007214, 4306708055122614542, 209823573154587335730, 10892496561736261641371, 600171728539156939466278
Offset: 0

Views

Author

Paul D. Hanna, Nov 20 2013

Keywords

Examples

			G.f.: A(x) = 1 + x + x^2 + 5*x^3 + 44*x^4 + 519*x^5 + 7590*x^6 + 132347*x^7 + 2689046*x^8 + 62644234*x^9 + 1651650774*x^10 +...
where
A(x) = 1 + x + x*(A(x)-1) + x*(A(x)^2-1)^2 + x*(A(x)^3-1)^3 + x*(A(x)^4-1)^4 + x*(A(x)^5-1)^5 + x*(A(x)^6-1)^6 + x*(A(x)^7-1)^7 +...
Also,
A(x) = 1 + x/2  +  x*A(x)/(1 + A(x))^2  +  x*A(x)^4/(1 + A(x)^2)^3  +  x*A(x)^9/(1 + A(x)^3)^4  +  x*A(x)^16/(1 + A(x)^4)^5  +  x*A(x)^25/(1 + A(x)^5)^6  + ...
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x); for(i=1, n, A=1+x*sum(m=0, n, (A^m-1+x*O(x^n))^m)); polcoeff(A, n)}
    for(n=0,20,print1(a(n),", "))

Formula

G.f. satisfies:
(1) A(x) = 1 + x*Sum_{n>=0} A(x)^(n^2) / (1 + A(x)^n)^(n+1). - Paul D. Hanna, Mar 31 2018
(2) A(x) = 1 + Series_Reversion(x/G(x))
(3) A(x) = 1 + x*G(A(x)-1)
where G(x) is the g.f. of A122400, the number of square (0,1)-matrices without zero rows and with exactly n entries equal to 1.
a(n) ~ c * d^n * n! / n^(3/2), where d = A317855 = (1+exp(1/r))*r^2 = 3.161088653865428813830172202588132491726382774188556341627278..., r = 0.8737024332396683304965683047207192982139922672025395099... is the root of the equation exp(1/r)/r + (1+exp(1/r))*LambertW(-exp(-1/r)/r) = 0, and c = 0.12140554666... . - Vaclav Kotesovec, May 07 2014

A317798 G.f.: Sum_{n>=0} (3*(1+x)^n - 1)^n / 3^(n+1).

Original entry on oeis.org

1, 15, 786, 69261, 8554530, 1359020643, 263929299177, 60582032629791, 16046282916588207, 4817035600778756553, 1616224504900354928832, 599373591433178971787007, 243449152911402772344286998, 107482020677618238226506065235, 51249638236281451846248205583562, 26247197050200652206165329786055981, 14369481728948627418149559363836673273
Offset: 0

Views

Author

Paul D. Hanna, Aug 14 2018

Keywords

Examples

			G.f.: A(x) = 1 + 15*x + 786*x^2 + 69261*x^3 + 8554530*x^4 + 1359020643*x^5 + 263929299177*x^6 + 60582032629791*x^7 + 16046282916588207*x^8 + ...
such that
A(x) = 1/3  +  (3*(1+x) - 1)/3^2  +  (3*(1+x)^2 - 1)^3/3^3  +  (3*(1+x)^3 - 1)^3/3^4  +  (3*(1+x)^4 - 1)^4/3^5  +  (3*(1+x)^5 - 1)^5/3^6  + ...
Also,
A(x) = 1/4  +  3*(1+x)/(3 + (1+x))^2  +  3^2*(1+x)^4/(3 + (1+x)^2)^3  +  3^3*(1+x)^9/(3 + (1+x)^3)^4  +  3^4*(1+x)^16/(3 + (1+x)^4)^5  +  3^5*(1+x)^25/(3 + (1+x)^5)^6  +  3^6*(1+x)^36/(3 + (1+x)^6)^7  + ...
		

Crossrefs

Formula

G.f. satisfies:
(1) Sum_{n>=0} 3^n * (1+x)^(n^2) / (3 + (1+x)^n)^(n+1).
(2) Sum_{n>=0} ((1+x)^n - 1/3)^n / 3.
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