A109708 -id:A109708 - cp's OEIS frontend

A281245 Expansion of Product_{k>=1} (1 + x^(7*k-1)).

1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 1, 3, 1, 0, 0, 0, 0, 2, 3, 1, 0, 0, 0, 0, 3, 4, 1, 0, 0, 0, 1, 4, 4, 1, 0, 0, 0, 1, 5, 5, 1, 0, 0, 0, 2, 7, 5, 1, 0, 0, 0

Offset: 0

Vaclav Kotesovec, Jan 18 2017

nonn

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

Cf. A262928, A147599, A281243, A281244.
Cf. A261612, A169975, A280454.
Cf. A109708, A281455, A281456, A281457, A281458, A280457, A281459.

nmax = 200; CoefficientList[Series[Product[(1 + x^(7*k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
nmax = 200; poly = ConstantArray[0, nmax + 1]; poly[[1]] = 1; poly[[2]] = 0; Do[If[Mod[k, 7] == 6, Do[poly[[j + 1]] += poly[[j - k + 1]], {j, nmax, k, -1}]; ], {k, 2, nmax}]; poly

a(n) ~ exp(sqrt(n/21)*Pi) / (2^(13/7)*21^(1/4)*n^(3/4)) * (1 + (13*Pi/(336*sqrt(21)) - 3*sqrt(21)/(8*Pi)) / sqrt(n)). - Vaclav Kotesovec, Jan 18 2017, extended Jan 24 2017

G.f.: Sum_{k>=0} x^(k*(7*k + 5)/2) / Product_{j=1..k} (1 - x^(7*j)). - Ilya Gutkovskiy, Nov 24 2020

A284105 a(n) = Sum_{d|n, d == 6 (mod 7)} d.

Original entry on oeis.org

0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 6, 13, 0, 0, 0, 0, 6, 0, 20, 0, 0, 0, 6, 0, 13, 27, 0, 0, 6, 0, 0, 0, 34, 0, 6, 0, 0, 13, 20, 41, 6, 0, 0, 0, 0, 0, 54, 0, 0, 0, 13, 0, 33, 55, 0, 0, 0, 0, 26, 0, 62, 0, 0, 13, 6, 0, 34, 69, 0, 0, 6, 0, 0, 0, 76, 0, 19, 0, 20, 27, 41

Offset: 1

Seiichi Manyama, Mar 20 2017

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Cf. A109708.
Cf. Sum_{d|n, d == k-1 (mod k)} d: A000593 (k=2), A078182 (k=3), A050452 (k=4), A284103 (k=5), A284104 (k=6), this sequence (k=7).
Cf. Sum_{d|n, d == k (mod 7)} d: A284099 (k=1), A284443 (k=2), A284444 (k=3), A284445 (k=4), A284446 (k=5), this sequence (k=6).

Table[Sum[If[Mod[d,7] == 6,d, 0], {d, Divisors[n]}], {n, 82}] (* Indranil Ghosh, Mar 21 2017 *)

for(n=1, 82, print1(sumdiv(n, d, if(Mod(d,7)==6, d, 0)),", ")) \\ Indranil Ghosh, Mar 21 2017

from sympy import divisors
def a(n): return sum([d for d in divisors(n) if d%7==6]) # Indranil Ghosh, Mar 21 2017

G.f.: Sum_{k>=1} (7*k - 1)*x^(7*k-1)/(1 - x^(7*k-1)). - Ilya Gutkovskiy, Mar 21 2017

Sum_{k=1..n} a(k) = c * n^2 + O(n*log(n)), where c = Pi^2/84 = 0.117495... . - Amiram Eldar, Nov 26 2023

A035462 Number of partitions of n into parts 4k-1.

Original entry on oeis.org

1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 2, 2, 1, 2, 3, 2, 2, 4, 4, 3, 4, 5, 5, 5, 6, 7, 8, 7, 8, 11, 10, 10, 13, 14, 14, 15, 17, 19, 20, 20, 24, 27, 26, 28, 33, 35, 35, 39, 44, 46, 48, 52, 58, 62, 63, 69, 78, 80, 83, 93, 100, 104, 111, 120, 130, 137, 143, 156, 169, 175, 185, 203

Offset: 0

Olivier Gérard

Also, number of partitions into parts 8k+3 or 8k+7.

Also number of partitions of n such that 2k-1 and 2k occur with the same multiplicity. Example: a(18)=3 because we have [8,7,2,1],[6,5,4,3] and [2,2,2,2,2,2,1,1,1,1,1,1]. It is easy to find a bijection between these partitions and those described in the definition. - Emeric Deutsch, Apr 05 2006

			a(18)=3 because we have [15,3],[11,7] and [3,3,3,3,3,3].

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000
James Mc Laughlin, Andrew V. Sills, Peter Zimmer, Rogers-Ramanujan-Slater Type Identities , arXiv:1901.00946 [math.NT]

Cf. A035441-A035468, A050452.

Cf. similar sequences of number of partitions of n into parts congruent to m-1 mod m: A000009 (m=2), A035386 (m=3), this sequence (m=4), A109700 (m=5), A109702 (m=6), A109708 (m=7).

g:=1/product(1-x^(4*i-1),i=1..50): gser:=series(g,x=0,80): seq(coeff(gser,x,n),n=1..75); # Emeric Deutsch, Apr 05 2006

nmax = 100; CoefficientList[Series[Product[1/(1-x^(4*k+3)),{k, 0, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Feb 26 2015 *)
nmax = 50; kmax = nmax/4; s = Range[0, kmax]*4 - 1;
Table[Count[IntegerPartitions@n, x_ /; SubsetQ[s, x]], {n, 0, nmax}] (* Robert Price, Aug 04 2020 *)

G.f.: 1/Product_{j>=1} (1 - x^(4*j-1)). - Emeric Deutsch, Apr 05 2006
G.f.: Sum_{n>=0} (x^(3*n) / Product_{k=1..n} (1 - x^(4*k))) = 1 + Sum_{n>=0} (x^(4*n+3) / Product_{k>=n} (1 - x^(4*k+3))) = 1 + Sum_{n>=0} (x^(4*n+3) / Product_{k=0..n} (1 - x^(4*k+3))). - Joerg Arndt, Apr 08 2011
a(n) ~ Pi^(3/4) * exp(Pi*sqrt(n/6)) / (Gamma(1/4) * 2^(13/8) * 3^(3/8) * n^(7/8)) * (1 + (Pi/(96*sqrt(6)) - 21*sqrt(3/2)/(16*Pi)) / sqrt(n)). - Vaclav Kotesovec, Feb 26 2015, extended Jan 24 2017
a(n) = (1/n)*Sum_{k=1..n} A050452(k)*a(n-k), a(0) = 1. - Seiichi Manyama, Mar 20 2017
From Peter Bala, Feb 02 2021: (Start)
G.f.: A(x) = Sum_{n >= 0} x^(n*(4*n-1))/Product_{k = 1..n} ( (1 - x^(4*k))*(1 - x^(4*k-1)) ). (Set z = x^3 and q = x^4 in Mc Laughlin et al., Section 1.3, Entry 7.)
Similarly, A(x) =  Sum_{n >= 0} x^(n*(4*n+3))/( (1 - x^3)*Product_{k = 1..n} ((1 - x^(4*k))*(1 - x^(4*k+3))) ). (End)

Offset changed by N. J. A. Sloane, Apr 11 2010

A109700 Number of partitions of n into parts each equal to 4 mod 5.

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 1, 2, 1, 1, 1, 2, 2, 2, 1, 2, 3, 4, 2, 2, 3, 5, 4, 3, 3, 6, 6, 6, 4, 6, 7, 9, 7, 7, 8, 11, 11, 11, 9, 12, 14, 16, 13, 14, 16, 21, 20, 19, 18, 24, 26, 27, 24, 27, 31, 36, 34, 34, 35, 43, 45, 47, 43, 49, 55, 62, 58, 59, 63, 75, 77, 77, 75, 87

Offset: 0

Erich Friedman, Aug 07 2005

nonn

			a(30)=2 since 30 = 14+4+4+4+4 = 9+9+4+4+4

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

Cf. A284103.

Cf. similar sequences of number of partitions of n into parts congruent to m-1 mod m: A000009 (m=2), A035386 (m=3), A035462 (m=4), this sequence (m=5), A109702 (m=6), A109708 (m=7).

g:=1/product(1-x^(4+5*j),j=0..25): gser:=series(g,x=0,95): seq(coeff(gser,x,n),n=0..90); # Emeric Deutsch, Mar 30 2006

nmax=100; CoefficientList[Series[Product[1/(1-x^(5*k+4)), {k, 0, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Feb 27 2015 *)

G.f.: 1/product(1-x^(4+5j), j=0..infinity). - Emeric Deutsch, Mar 30 2006
a(n) ~ Gamma(4/5) * exp(Pi*sqrt(2*n/15)) / (2^(19/10) * 3^(2/5) * 5^(1/10) * Pi^(1/5) * n^(9/10)) * (1 - (9*sqrt(6/5)/(5*Pi) + Pi/(120*sqrt(30))) / sqrt(n)). - Vaclav Kotesovec, Feb 27 2015, extended Jan 24 2017
a(n) = (1/n)*Sum_{k=1..n} A284103(k)*a(n-k), a(0) = 1. - Seiichi Manyama, Mar 20 2017

More terms from Michael Somos, Aug 10 2005

A109702 Number of partitions of n into parts each equal to 5 mod 6.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 2, 1, 0, 1, 1, 2, 2, 1, 1, 1, 2, 3, 3, 2, 1, 2, 3, 4, 4, 2, 2, 3, 5, 6, 5, 3, 3, 5, 7, 8, 6, 4, 5, 8, 10, 10, 8, 6, 8, 11, 13, 13, 10, 9, 12, 15, 18, 17, 14, 13, 16, 21, 23, 22, 18, 18, 23, 28, 31, 28, 24, 25, 31, 38, 39, 36, 32, 34

Offset: 0

Erich Friedman, Aug 07 2005

nonn

			a(40)=4 since 40 = 35+5 = 29+11 = 23+17 = 5+5+5+5+5+5+5+5.

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

Cf. A284104.

Cf. similar sequences of number of partitions of n into parts congruent to m-1 mod m: A000009 (m=2), A035386 (m=3), A035462 (m=4), A109700 (m=5), this sequence (m=6), A109708 (m=7).

g:=1/product(1-x^(5+6*j),j=0..20): gser:=series(g,x=0,92): seq(coeff(gser,x,n),n=0..89); # Emeric Deutsch, Apr 14 2006

nmax=100; CoefficientList[Series[Product[1/(1-x^(6*k+5)),{k, 0, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Feb 27 2015 *)
Table[Count[IntegerPartitions[n],?(Union[Mod[#,6]]=={5}&)],{n,0,90}] (* _Harvey P. Dale, Mar 08 2022 *)

G.f.: 1/product(1-x^(5+6j),j=0..infinity). - Emeric Deutsch, Apr 14 2006
a(n) ~ Gamma(5/6) * exp(Pi*sqrt(n)/3) / (4 * sqrt(3) * Pi^(1/6) * n^(11/12)) * (1 - (55/(24*Pi) + Pi/144) / sqrt(n)). - Vaclav Kotesovec, Feb 27 2015, extended Jan 24 2017
a(n) = (1/n)*Sum_{k=1..n} A284104(k)*a(n-k), a(0) = 1. - Seiichi Manyama, Mar 20 2017
Euler transform of period 6 sequence [ 0, 0, 0, 0, 1, 0, ...]. - Kevin T. Acres, Apr 28 2018

Changed offset to 0 and added a(0)=1 by Vaclav Kotesovec, Feb 27 2015

A035430 Number of partitions of n into parts 7k+1 or 7k+6.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 3, 3, 4, 5, 6, 7, 8, 8, 9, 10, 12, 14, 16, 17, 19, 20, 23, 26, 30, 33, 37, 39, 43, 47, 53, 59, 66, 71, 77, 83, 92, 101, 113, 123, 134, 144, 156, 169, 187, 204, 223, 240, 259, 278, 303, 329, 360, 389, 420, 449, 485, 522, 567, 613, 663, 710, 763

Offset: 0

Olivier Gérard

nonn

Convolution of A109708 and A109703. - Vaclav Kotesovec, Jan 21 2017

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

Cf. A284151.

nmax = 100; CoefficientList[Series[Product[1/((1 - x^(7k+1))*(1 - x^(7k+6))), {k, 0, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 26 2015 *)

a(n) ~ exp(2*Pi*sqrt(n/21)) / (4 * 21^(1/4) * sin(Pi/7) * n^(3/4)) * (1 - (3*sqrt(21)/(16*Pi) + 13*Pi/(84*sqrt(21))) / sqrt(n)). - Vaclav Kotesovec, Aug 26 2015, extended Jan 24 2017

a(n) = (1/n)*Sum_{k=1..n} A284151(k)*a(n-k), a(0) = 1. - Seiichi Manyama, Mar 21 2017

Prepended a(0)=1 from Vaclav Kotesovec, Jan 23 2017

cp's OEIS Frontend

A281245 Expansion of Product_{k>=1} (1 + x^(7*k-1)).

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A284105 a(n) = Sum_{d|n, d == 6 (mod 7)} d.

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A035462 Number of partitions of n into parts 4k-1.

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A109700 Number of partitions of n into parts each equal to 4 mod 5.

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A109702 Number of partitions of n into parts each equal to 5 mod 6.

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A035430 Number of partitions of n into parts 7k+1 or 7k+6.

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