A002295 -id:A002295 - cp's OEIS frontend

A365193 G.f. satisfies A(x) = 1 + xA(x)^5 / (1 - xA(x)^3).

1, 1, 6, 49, 463, 4760, 51702, 583712, 6781774, 80555066, 973813974, 11941861079, 148191437719, 1857464450449, 23481830726334, 299056887494427, 3833349330581255, 49416395972195630, 640256115370243620, 8332835556325119938, 108890550249605779116

Offset: 0

Seiichi Manyama, Aug 25 2023

nonn

Cf. A002295, A243667, A349332, A364748, A365192, A365194.

Cf. A365187.

a(n) = sum(k=0, n, binomial(3*n+2*k+1, k)*binomial(n-1, n-k)/(3*n+2*k+1));

a(n) = Sum_{k=0..n} binomial(3*n+2*k+1,k) * binomial(n-1,n-k)/(3*n+2*k+1).

A382001 E.g.f. A(x) satisfies A(x) = 1 + xexp(2x)*A(x)^6.

Original entry on oeis.org

1, 1, 16, 462, 20672, 1261400, 97728672, 9190016416, 1016963389696, 129485497897728, 18648682990461440, 2997567408967391744, 531985786683988512768, 103321584851593487961088, 21798243872991807130685440, 4964302861788729054456729600, 1213816740632458735310221672448

Offset: 0

Seiichi Manyama, Mar 12 2025

nonn

In general, if k>1 and e.g.f. A(x) satisfies A(x) = 1 + x*exp(2*x)*A(x)^k, then a(n) ~ sqrt(k) * sqrt(1 + LambertW(2*(k-1)^(k-1)/k^k)) * 2^n * n^(n-1) / ((k-1)^(3/2) * exp(n) * LambertW(2*(k-1)^(k-1)/k^k)^n). - Vaclav Kotesovec, Mar 22 2025

Cf. A336950, A381997, A381998, A381999, A382000.

Cf. A002295, A381989.

a(n) = n!*sum(k=0, n, (2*k)^(n-k)*binomial(6*k+1, k)/((6*k+1)*(n-k)!));

a(n) = n! * Sum_{k=0..n} (2*k)^(n-k) * A002295(k)/(n-k)!.

a(n) ~ sqrt(3*(1 + LambertW(3125/23328))) * 2^(n + 1/2) * n^(n-1) / (5^(3/2) * exp(n) * LambertW(3125/23328)^n). - Vaclav Kotesovec, Mar 22 2025

A386567 a(n) = Sum_{k=0..n-1} binomial(6k-1,k) binomial(6n-6k,n-k-1).

Original entry on oeis.org

0, 1, 17, 268, 4129, 62955, 954392, 14417376, 217279857, 3269099590, 49125066135, 737516631908, 11064270530632, 165889863957065, 2486052264852180, 37241727274394640, 557707191712371729, 8349517132932620730, 124971965902300790390, 1870139909398530770760

Offset: 0

Seiichi Manyama, Jul 26 2025

nonn

			(1/5) * log( Sum_{k>=0} binomial(6*k-1,k)*x^k ) = x + 17*x^2/2 + 268*x^3/3 + 4129*x^4/4 + 12591*x^5 + ...

Cf. A000346, A062236, A386565, A386566.
Cf. A079679, A386368, A386615, A386616.
Cf. A002295, A130564.

a(n) = sum(k=0, n-1, binomial(6*k-1, k)*binomial(6*n-6*k, n-k-1));

my(N=20, x='x+O('x^N), g=sum(k=0, N, binomial(6*k, k)/(5*k+1)*x^k)); concat(0, Vec(g*(g-1)/(6-5*g)^2))

G.f.: g*(g-1)/(6-5*g)^2 where g=1+x*g^6.
G.f.: g/(1-6*g)^2 where g*(1-g)^5 = x.
L.g.f.: Sum_{k>=1} a(k)*x^k/k = (1/5) * log( Sum_{k>=0} binomial(6*k-1,k)*x^k ).
a(n) = Sum_{k=0..n-1} binomial(6*k-1+l,k) * binomial(6*n-6*k-l,n-k-1) for every real number l.
a(n) = Sum_{k=0..n-1} 5^(n-k-1) * binomial(6*n,k).
a(n) = Sum_{k=0..n-1} 6^(n-k-1) * binomial(5*n+k,k).

A206290 G.f.: Sum_{n>=0} Product_{k=1..n} Series_Reversion( x/(1 + x^k) ).

Original entry on oeis.org

1, 1, 2, 3, 5, 7, 12, 17, 29, 44, 77, 114, 218, 330, 617, 987, 1913, 2968, 6068, 9500, 19263, 31399, 64268, 101702, 218891, 348559, 735823, 1205239, 2576727, 4119884, 9100854, 14588992, 31841260, 52163378, 114485092, 183947681, 414704366, 667453931, 1487920000

Offset: 0

Paul D. Hanna, Feb 05 2012

nonn

Compare to the g.f. of partition numbers (A000041): Sum_{n>=0} Product_{k=1..n} x/(1 - x^k).

			G.f.: A(x) = 1 + x + 2*x^2 + 3*x^3 + 5*x^4 + 7*x^5 + 12*x^6 + 17*x^7 +...
such that, by definition,
A(x) = 1 + G_1(x) + G_1(x)*G_2(x) + G_1(x)*G_2(x)*G_3(x) + G_1(x)*G_2(x)*G_3(x)*G_4(x) +...
where G_n( x/(1 + x^n) ) = x.
The first few expansions of G_n(x) begin:
G_1(x) = x + x^2 + x^3 + x^4 + x^5 + x^6 +...+ x^(n+1) +...
G_2(x) = x + x^3 + 2*x^5 + 5*x^7 + 14*x^9 +...+ A000108(n)*x^(2*n+1) +...
G_3(x) = x + x^4 + 3*x^7 + 12*x^10 + 55*x^13 +...+ A001764(n)*x^(3*n+1) +...
G_4(x) = x + x^5 + 4*x^9 + 22*x^13 + 140*x^17 +...+ A002293(n)*x^(4*n+1) +...
G_5(x) = x + x^6 + 5*x^11 + 35*x^16 + 285*x^21 +...+ A002294(n)*x^(5*n+1) +...
G_6(x) = x + x^7 + 6*x^13 + 51*x^19 + 506*x^25 +...+ A002295(n)*x^(6*n+1) +...
G_7(x) = x + x^8 + 7*x^15 + 70*x^22 + 819*x^29 +...+ A002296(n)*x^(7*n+1) +...
Note that G_n(x) = x + x*G_n(x)^n.

Vaclav Kotesovec, Table of n, a(n) for n = 0..250

Cf. A206289, A194560, A110448.

{a(n)=polcoeff(sum(m=0,n,prod(k=1,m,serreverse(x/(1+x^k+x*O(x^n))))),n)}
for(n=0,45,print1(a(n),", "))

G.f.: Sum_{n>=0} Product_{k=1..n} G_k(x), where G_n(x) is defined by:
(1) G_n(x) = Series_Reversion( x/(1 + x^n) ),
(2) G_n(x) = x + x*G_n(x)^n,
(3) G_n(x) = Sum_{k>=0} binomial(n*k+1, k) * x^(n*k+1) / (n*k+1).

A226910 a(n) = Sum_{k=0..floor(n/5)} binomial(n,5k)binomial(6k,k)/(5k+1).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 7, 22, 57, 127, 259, 529, 1189, 3004, 8009, 21073, 53233, 129813, 312733, 763573, 1915251, 4914736, 12720841, 32800186, 83869501, 213261712, 542609237, 1388542312, 3579043987, 9273567337, 24075321925, 62475528190, 161969731985, 419914766965

Offset: 0

Karol A. Penson, Jun 22 2013

Alois P. Heinz, Table of n, a(n) for n = 0..750

Cf. A002295, A049130, A212385, A227035.

Table[Sum[Binomial[n,5*k]*Binomial[6*k,k]/(5*k+1),{k,0,Floor[n/5]}],{n,0,20}] (* Vaclav Kotesovec, Jun 28 2013 *)

a(n)=sum(k=0,n\5,binomial(n,5*k)*binomial(6*k,k)/(5*k+1)) \\ Charles R Greathouse IV, Jun 24 2013

Representation in terms of special values of generalized hypergeometric function of type 10F9: a(n) = hypergeom([1/6, 1/3, 1/2, 2/3, 5/6, -(1/5)*n, -(1/5)*n+4/5, -(1/5)*n+3/5, -(1/5)*n+2/5, 1/5-(1/5)*n], [1/5, 2/5, 2/5, 3/5, 3/5, 4/5, 4/5, 1, 6/5], -6^6/5^5), n>=0.
Recurrence: -49781*(n-9)*(n-8)*(n-7)*(n-6)*(n-5)*a(n-10) + 10*(n-8)*(n-7)*(n-6)*(n-5)*(26453*n - 123726)*a(n-9) - 15*(n-7)*(n-6)*(n-5)*(40479*n^2 - 351957*n + 782140)*a(n-8) + 120*(n-6)*(n-5)*(7013*n^3 - 87699*n^2 + 378278*n - 565577)*a(n-7) - 6*(n-5)*(148255*n^4 - 2435310*n^3 + 15491085*n^2 - 45173430*n + 50791476)*a(n-6) + 12*(69513*n^5 - 1361100*n^4 + 10838875*n^3 - 43818750*n^2 + 89776250*n - 74437500)*a(n-5) - 93750*(7*n^4 - 98*n^3 + 525*n^2 - 1274*n + 1180)*(n-3)*a(n-4) + 375000*(n-2)*(n^2-6*n+10)*(n-3)^2*a(n-3) - 46875*(n-2)*(n-1)*(3*n^2-15*n+20)*(n-3)*a(n-2) + 31250*(n-2)^2*(n-1)*n*(n-3)*a(n-1) - 3125*(n-2)*(n-1)*n*(n+1)*(n-3)*a(n) = 0. - Vaclav Kotesovec, Jun 28 2013
a(n) ~ (5+6^(1+1/5))^(n+3/2)/(5^(n+1)*6^(1+3/10)*sqrt(2*Pi)*n^(3/2)). - Vaclav Kotesovec, Jun 28 2013
G.f. A(x) satisfies: A(x) = 1 / (1 - x) + x^5 * A(x)^6. - Ilya Gutkovskiy, Jul 25 2021
From Peter Bala, Sep 15 2021: (Start)
O.g.f.: A(x) = (1/x)*series reversion ( x*(1 - x^5)/(1 + x*(1 - x^5)) ).
The g.f. of the m-th binomial transform of this sequence is equal to (1/x)*series reversion ( x*(1 - x^5)/(1 + (m + 1)*x*(1 - x^5)) ). The case m = -1 gives the sequence [1, 0, 0, 0, 0, 1, 0, 0,0, 0, 6, 0, 0, 0, 0, 51, 0, 0, 0, 0, 506, ...] - an aerated version of A002295. (End)

A233827 a(n) = 8binomial(6n+8,n)/(6*n+8).

Original entry on oeis.org

1, 8, 76, 800, 8990, 105672, 1283464, 15981504, 202927725, 2617624680, 34206162848, 451872681728, 6024664312030, 80964348872400, 1095590286231120, 14915165412813184, 204140673966231870, 2807362363541687280, 38772186055550141700

Offset: 0

Tim Fulford, Dec 16 2013

nonn

Fuss-Catalan sequence is a(n,p,r) = r*binomial(np+r,n)/(np+r), this is the case p=6, r=8.

Vincenzo Librandi, Table of n, a(n) for n = 0..200
J-C. Aval, Multivariate Fuss-Catalan Numbers, arXiv:0711.0906v1, Discrete Math., 308 (2008), 4660-4669.
Thomas A. Dowling, Catalan Numbers Chapter 7
Wojciech Mlotkowski, Fuss-Catalan Numbers in Noncommutative Probability, Docum. Mathm. 15: 939-955.

Cf. A000108, A002295, A212071, A212072, A212073, A130564, A233743, A233829, A233830.

[8*Binomial(6*n+8, n)/(6*n+8): n in [0..30]];

Table[8 Binomial[6 n + 8, n]/(6 n + 8), {n, 0, 30}]

PARI
```
a(n) = 8*binomial(6*n+8,n)/(6*n+8);
```

{a(n)=local(B=1); for(i=0, n, B=(1+x*B^(6/8))^8+x*O(x^n)); polcoeff(B, n)}

G.f. satisfies: B(x) = {1 + x*B(x)^(p/r)}^r, where p=6, r=8.
From Ilya Gutkovskiy, Sep 14 2018: (Start)
E.g.f.: 5F5(4/3,3/2,5/3,11/6,13/6; 1,9/5,11/5,12/5,13/5; 46656*x/3125).
a(n) ~ 3^(6*n+15/2)*4^(3*n+5)/(sqrt(Pi)*5^(5*n+17/2)*n^(3/2)). (End)
D-finite with recurrence 5*n*(5*n+6)*(5*n+7)*(5*n+8)*(5*n+4)*a(n) -72*(6*n+5)*(3*n+2)*(2*n+1)*(3*n+1)*(6*n+7)*a(n-1)=0. - R. J. Mathar, Nov 22 2024

A233829 a(n) = 3binomial(6n+9,n)/(2*n+3).

Original entry on oeis.org

1, 9, 90, 975, 11160, 132867, 1629012, 20430900, 260907075, 3381098545, 44352058608, 587787511779, 7858257798300, 105855415586550, 1435361957277480, 19576154604317304, 268364706225271110, 3695862686045572350, 51108790709588823150

Offset: 0

Tim Fulford, Dec 16 2013

nonn

Fuss-Catalan sequence is a(n,p,r) = r*binomial(np+r,n)/(np+r), this is the case p=6, r=9.

Vincenzo Librandi, Table of n, a(n) for n = 0..200
J-C. Aval, Multivariate Fuss-Catalan Numbers, arXiv:0711.0906v1, Discrete Math., 308 (2008), 4660-4669.
Thomas A. Dowling, Catalan Numbers Chapter 7
Wojciech Mlotkowski, Fuss-Catalan Numbers in Noncommutative Probability, Docum. Mathm. 15: 939-955.

Cf. A000108, A002295, A212071, A212072, A212073, A130564, A233743, A233827, A233830.

[3*Binomial(6*n+9, n)/(2*n+3): n in [0..30]];

Table[3 Binomial[6 n + 9, n]/(2 n + 3), {n, 0, 30}]

PARI
```
a(n) = 3*binomial(6*n+9,n)/(2*n+3);
```

{a(n)=local(B=1); for(i=0, n, B=(1+x*B^(2/3))^9+x*O(x^n)); polcoeff(B, n)}

G.f. satisfies: B(x) = {1 + x*B(x)^(p/r)}^r, where p=6, r=9.
From Ilya Gutkovskiy, Sep 14 2018: (Start)
E.g.f.: 5F5(3/2,5/3,11/6,13/6,7/3; 1,11/5,12/5,13/5,14/5; 46656*x/3125).
a(n) ~ 3^(6*n+21/2)*4^(3*n+4)/(sqrt(Pi)*5^(5*n+19/2)*n^(3/2)). (End)

A233830 a(n) = 5binomial(6n+10,n)/(3*n+5).

Original entry on oeis.org

1, 10, 105, 1170, 13640, 164502, 2036265, 25727800, 330482295, 4303216330, 56672074888, 753573733050, 10103474312100, 136435868978220, 1854009194816745, 25333847134998864, 347880174736462550, 4798137522234602700, 66441427922465470095, 923346006310186106010, 12873823246049001482400

Offset: 0

Tim Fulford, Dec 16 2013

nonn

Fuss-Catalan sequence is a(n,p,r) = r*binomial(np+r,n)/(np+r), this is the case p=6, r=10.

Vincenzo Librandi, Table of n, a(n) for n = 0..200
J-C. Aval, Multivariate Fuss-Catalan Numbers, arXiv:0711.0906v1, Discrete Math., 308 (2008), 4660-4669.
Thomas A. Dowling, Catalan Numbers Chapter 7
Wojciech Mlotkowski, Fuss-Catalan Numbers in Noncommutative Probability, Docum. Mathm. 15: 939-955.

Cf. A000108, A002295, A212071, A212072, A212073, A130564, A233743, A233827, A233829.

[5*Binomial(6*n+10, n)/(3*n+5): n in [0..30]];

Table[5 Binomial[6 n + 10, n]/(3 n + 5), {n, 0, 30}]

PARI
```
a(n) = 5*binomial(6*n+10,n)/(3*n+5);
```

{a(n)=local(B=1); for(i=0, n, B=(1+x*B^(3/5))^10+x*O(x^n)); polcoeff(B, n)}

G.f. satisfies: B(x) = {1 + x*B(x)^(p/r)}^r, here p=6, r=10.
From Ilya Gutkovskiy, Sep 14 2018: (Start)
E.g.f.: 6F6(5/3,11/6,2,13/6,7/3,5/2; 1,11/5,12/5,13/5,14/5,3; 46656*x/3125).
a(n) ~ 3^(6*n+19/2)*4^(3*n+5)/(sqrt(Pi)*5^(5*n+19/2)*n^(3/2)). (End)

A235534 a(n) = binomial(6n, 2n) / (4*n + 1).

Original entry on oeis.org

1, 3, 55, 1428, 43263, 1430715, 50067108, 1822766520, 68328754959, 2619631042665, 102240109897695, 4048514844039120, 162250238001816900, 6568517413771094628, 268225186597703313816, 11034966795189838872624, 456949965738717944767791

Offset: 0

Bruno Berselli, Jan 12 2014

This is the case l=4, k=2 of binomial((l+k)*n,k*n)/((l*n+1)/gcd(k,l*n+1)), see Theorem 1.1 in Zhi-Wei Sun's paper.

First bisection of A001764.

Zhi-Wei Sun, On Divisibility Of Binomial Coefficients, Journal of the Australian Mathematical Society 93 (2012), p. 189-201.

Cf. similar sequences generated by binomial((l+k)*n,k*n)/(l*n+1), where l is divisible by all the factors of k: A000108 (l=1, k=1), A001764 (l=2, k=1), A002293 (l=3, k=1), A002294 (l=4, k=1), A002295 (l=5, k=1), A002296 (l=6, k=1), A007556 (l=7, k=1), A062994 (l=8, k=1), A059968 (l=9, k=1), A230388 (l=10, k=1), A048990 (l=2, k=2), this sequence (l=4, k=2), A235536 (l=6, k=2), A187357 (l=3, k=3), A235535 (l=6, k=3).

l:=4; k:=2; [Binomial((l+k)*n,k*n)/(l*n+1): n in [0..20]]; /* where l is divisible by all the prime factors of k */

Table[Binomial[6 n, 2 n]/(4 n + 1), {n, 0, 20}]

a(n) = A047749(4*n-2) for n>0.
From Ilya Gutkovskiy, Jun 21 2018: (Start)
G.f.: 4F3(1/6,1/3,2/3,5/6; 1/2,3/4,5/4; 729*x/16).
a(n) ~ 3^(6*n+1/2)/(sqrt(Pi)*2^(4*n+7/2)*n^(3/2)). (End)

A235535 a(n) = binomial(9n, 3n) / (6*n + 1).

Original entry on oeis.org

1, 12, 1428, 246675, 50067108, 11124755664, 2619631042665, 642312451217745, 162250238001816900, 41932353590942745504, 11034966795189838872624, 2946924270225408943665279, 796607831560617902288322405, 217550867863011281855594752680

Offset: 0

Bruno Berselli, Jan 12 2014

This is the case l=6, k=3 of binomial((l+k)*n,k*n)/((l*n+1)/gcd(k,l*n+1)), see Theorem 1.1 in Zhi-Wei Sun's paper.

Also, the sequence follows A002296 and A235536, namely binomial(7*n,n)/(6*n+1) and binomial(8*n,2*n)/(6*n+1); naturally, even binomial(10*n,4*n)/(6*n+1) is always integer.

Robert Israel, Table of n, a(n) for n = 0..403
Zhi-Wei Sun, On Divisibility Of Binomial Coefficients, Journal of the Australian Mathematical Society 93 (2012), p. 189-201.

Cf. similar sequences generated by binomial((l+k)*n,k*n)/(l*n+1), where l is divisible by all the factors of k: A000108 (l=1, k=1), A001764 (l=2, k=1), A002293 (l=3, k=1), A002294 (l=4, k=1), A002295 (l=5, k=1), A002296 (l=6, k=1), A007556 (l=7, k=1), A062994 (l=8, k=1), A059968 (l=9, k=1), A230388 (l=10, k=1), A048990 (l=2, k=2), A235534 (l=4, k=2), A235536 (l=6, k=2), A187357 (l=3, k=3), this sequence (l=6, k=3).

l:=6; k:=3; [Binomial((l+k)*n,k*n)/(l*n+1): n in [0..20]]; /* here l is divisible by all the prime factors of k */

seq(binomial(9*n,3*n)/(6*n+1), n=0..30); # Robert Israel, Feb 15 2021

Table[Binomial[9 n, 3 n]/(6 n + 1), {n, 0, 20}]

a(n) = A001764(3*n) = A047749(6*n).
From Ilya Gutkovskiy, Jun 21 2018: (Start)
G.f.: 6F5(1/9,2/9,4/9,5/9,7/9,8/9; 1/3,1/2,2/3,5/6,7/6; 19683*x/64).
a(n) ~ 3^(9*n-1)/(sqrt(Pi)*4^(3*n+1)*n^(3/2)). (End)
D-finite with recurrence 8*(6*n + 5)*(2*n + 1)*(n + 1)*(3*n + 2)*(3*n + 1)*(6*n + 7)*a(n + 1) = 3*(9*n + 8)*(9*n + 7)*(9*n + 5)*(9*n + 4)*(9*n + 2)*(9*n + 1)*a(n). - Robert Israel, Feb 15 2021

cp's OEIS Frontend

A365193 G.f. satisfies A(x) = 1 + x*A(x)^5 / (1 - x*A(x)^3).

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A382001 E.g.f. A(x) satisfies A(x) = 1 + x*exp(2*x)*A(x)^6.

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A386567 a(n) = Sum_{k=0..n-1} binomial(6*k-1,k) * binomial(6*n-6*k,n-k-1).

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A206290 G.f.: Sum_{n>=0} Product_{k=1..n} Series_Reversion( x/(1 + x^k) ).

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A226910 a(n) = Sum_{k=0..floor(n/5)} binomial(n,5*k)*binomial(6*k,k)/(5*k+1).

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A233827 a(n) = 8*binomial(6*n+8,n)/(6*n+8).

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A233829 a(n) = 3*binomial(6*n+9,n)/(2*n+3).

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A233830 a(n) = 5*binomial(6*n+10,n)/(3*n+5).

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A365193 G.f. satisfies A(x) = 1 + xA(x)^5 / (1 - xA(x)^3).

A382001 E.g.f. A(x) satisfies A(x) = 1 + xexp(2x)*A(x)^6.

A386567 a(n) = Sum_{k=0..n-1} binomial(6k-1,k) binomial(6n-6k,n-k-1).

A226910 a(n) = Sum_{k=0..floor(n/5)} binomial(n,5k)binomial(6k,k)/(5k+1).

A233827 a(n) = 8binomial(6n+8,n)/(6*n+8).

A233829 a(n) = 3binomial(6n+9,n)/(2*n+3).

A233830 a(n) = 5binomial(6n+10,n)/(3*n+5).

A235534 a(n) = binomial(6n, 2n) / (4*n + 1).

A235535 a(n) = binomial(9n, 3n) / (6*n + 1).