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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A057781 a(n) = n^4+4 = (n^2-2*n+2)*(n^2+2*n+2) = ((n-1)^2+1)*((n+1)^2+1).

Original entry on oeis.org

4, 5, 20, 85, 260, 629, 1300, 2405, 4100, 6565, 10004, 14645, 20740, 28565, 38420, 50629, 65540, 83525, 104980, 130325, 160004, 194485, 234260, 279845, 331780, 390629, 456980, 531445, 614660, 707285, 810004, 923525, 1048580, 1185925
Offset: 0

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Author

Henry Bottomley, Nov 04 2000

Keywords

References

  • Donald E. Knuth, The Art of Computer Programming, Addison-Wesley, Reading, MA, 1997, Vol. 1, exercise 1.2.1, Nr. 11, p. 19. [From Reinhard Zumkeller, Apr 11 2010]

Crossrefs

Programs

Formula

G.f.: -(5*x^4-5*x^3+35*x^2-15*x+4) / (x-1)^5. - Colin Barker, Mar 29 2013
a(n) = A002523(n) + 3.
a(n) = A002522(n-1) * A002522(n+1).
Sum_{k=0..n} A033999(k)*A016755(k)/a(k) = A033999(n)*(n+1)/A053755(n+1), see Knuth reference. - Reinhard Zumkeller, Apr 11 2010
a(n) = (n^2)^2 + 2^2 = (n^2-2)^2 + (2*n)^2. - Thomas Ordowski, Sep 15 2015
a(n) = A272298(3*n)/3^4. - Bruno Berselli, Apr 29 2016
Sum_{n>=0} 1/a(n) = (Pi*coth(Pi) + 1)/8. - Amiram Eldar, Oct 04 2021

A287091 Expansion of Product_{k>=1} 1/(1 - x^((2*k-1)^3)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5
Offset: 0

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Author

Ilya Gutkovskiy, May 19 2017

Keywords

Comments

Number of partitions of n into odd cubes.
In general, if m > 0 and g.f. = Product_{k>=1} 1/(1 - x^((2*k-1)^m)), then a(n) ~ exp((m+1) * (Gamma(1/m) * Zeta(1+1/m) / (2*m^2))^(m/(m+1)) * n^(1/(m+1))) * (Gamma(1/m) * Zeta(1+1/m))^(m/(2*(m+1))) / (sqrt(Pi*(m+1)) * 2^((1+m*(m+3))/(2*(m+1))) * m^((m-1)/(2*(m+1))) * n^((2*m+1)/(2*(m+1)))). - Vaclav Kotesovec, Sep 19 2017

Examples

			a(27) = 2 because we have [27] and [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1].
		

Crossrefs

Programs

  • Mathematica
    nmax = 110; CoefficientList[Series[Product[1/(1 - x^((2*k-1)^3)), {k, 1, Floor[nmax^(1/3)/2] + 1}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 18 2017 *)

Formula

G.f.: Product_{k>=1} 1/(1 - x^((2*k-1)^3)).
a(n) ~ exp(2^(5/4) * (Gamma(1/3) * Zeta(4/3))^(3/4) * n^(1/4) / 3^(3/2)) * (Gamma(1/3) * Zeta(4/3)/2)^(3/8) / (8 * 3^(1/4) * sqrt(Pi) * n^(7/8)). - Vaclav Kotesovec, Sep 18 2017

A290276 Numbers that are the sum of distinct odd positive cubes.

Original entry on oeis.org

1, 27, 28, 125, 126, 152, 153, 343, 344, 370, 371, 468, 469, 495, 496, 729, 730, 756, 757, 854, 855, 881, 882, 1072, 1073, 1099, 1100, 1197, 1198, 1224, 1225, 1331, 1332, 1358, 1359, 1456, 1457, 1483, 1484, 1674, 1675, 1701, 1702, 1799, 1800, 1826, 1827, 2060, 2061, 2087, 2088, 2185, 2186, 2197, 2198, 2212
Offset: 1

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Author

Ilya Gutkovskiy, Jul 25 2017

Keywords

Comments

Complement of A292740.

Examples

			881 is in the sequence because 881 = 27 + 125 + 729 = 3^3 + 5^3 + 9^3.
		

Crossrefs

Programs

  • Maple
    N:= 10000: # to get all terms <= N
    M:= floor(N^(1/3)):
    G:= mul(1+x^(j^3),j=1..M,2):
    S:= series(G,x,N+1):
    select(t -> coeff(S,x,t)>0, [$1..N]); # Robert Israel, Jul 26 2017
  • Mathematica
    max = 2212; f[x_] := Product[1 + x^(2 k + 1)^3, {k, 0, 8}]; Exponent[#, x] & /@ List @@ Normal[Series[f[x], {x, 0, max}]] // Rest

A309335 a(n) = n^3 if n odd, 7*n^3/8 if n even.

Original entry on oeis.org

0, 1, 7, 27, 56, 125, 189, 343, 448, 729, 875, 1331, 1512, 2197, 2401, 3375, 3584, 4913, 5103, 6859, 7000, 9261, 9317, 12167, 12096, 15625, 15379, 19683, 19208, 24389, 23625, 29791, 28672, 35937, 34391, 42875, 40824, 50653, 48013, 59319, 56000, 68921, 64827, 79507, 74536, 91125
Offset: 0

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Author

Ilya Gutkovskiy, Jul 24 2019

Keywords

Comments

Moebius transform of A007331.

Crossrefs

Programs

  • Mathematica
    a[n_] := If[OddQ[n], n^3, 7 n^3/8]; Table[a[n], {n, 0, 45}]
    nmax = 45; CoefficientList[Series[x (1 + 7 x + 23 x^2 + 28 x^3 + 23 x^4 + 7 x^5 + x^6)/(1 - x^2)^4, {x, 0, nmax}], x]
    LinearRecurrence[{0, 4, 0, -6, 0, 4, 0, -1}, {0, 1, 7, 27, 56, 125, 189, 343}, 46]
    Table[n^3 (15 - (-1)^n)/16, {n, 0, 45}]

Formula

G.f.: x * (1 + 7*x + 23*x^2 + 28*x^3 + 23*x^4 + 7*x^5 + x^6)/(1 - x^2)^4.
G.f.: Sum_{k>=1} J_3(k) * x^k/(1 - x^(2*k)), where J_3() is the Jordan function (A059376).
Dirichlet g.f.: zeta(s-3) * (1 - 1/2^s).
a(n) = n^3 * (15 - (-1)^n)/16.
a(n) = Sum_{d|n, n/d odd} J_3(d).
Sum_{n>=1} 1/a(n) = 57*zeta(3)/56 = 1.223522205001729897639...
Multiplicative with a(2^e) = 7*2^(3*e-3), and a(p^e) = p^(3*e) for odd primes p. - Amiram Eldar, Oct 26 2020
Euler transform is A248882. - Georg Fischer, Nov 10 2020

A383368 Number of intercalates in pine Latin squares of order 2n.

Original entry on oeis.org

1, 12, 27, 80, 125, 252, 343, 576, 729, 1100, 1331, 1872, 2197, 2940, 3375, 4352, 4913, 6156, 6859, 8400, 9261, 11132, 12167, 14400, 15625
Offset: 1

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Author

Eduard I. Vatutin, Apr 24 2025

Keywords

Comments

Pine Latin square is a none canonical composite Latin square of order N=2*K formed from specially arranged cyclic Latin squares of order K.
By construction, pine Latin square is determined one-to-one by the cyclic square used, so number of pine Latin squares of order N is equal to number of cyclic Latin squares of order N/2.
All pine Latin squares are horizontally symmetric column-inverse Latin squares.
All pine Latin squares for selected order N are isomorphic one to another as Latin squares, so they have same properties (number of transversals, intercalates, etc.).
Pine Latin squares have interesting properties, for example, maximum known number of intercalates for some orders N (at least N in {2, 4, 6, 10, 18}).
Pine Latin squares do not exist for odd orders due to they are horizontally symmetric.
Pine Latin squares of order N=2n exists for all even orders due to existing of corresponding cyclic Latin squares of order n. According to this, maximum number of intercalates in a Latin square A092237(N) >= (2k)^2 * (2k + 1) for N=4k and A092237(N) >= (2k+1)^3 for N=4k+2. Therefore, asimptotically maximum number of intercalates in Latin squares of even orders N greater or equal than o(k1*N^3), where k1 = 1/8.

Examples

			For order N=8 pine Latin square
  0 1 2 3 4 5 6 7
  1 2 3 0 7 4 5 6
  2 3 0 1 6 7 4 5
  3 0 1 2 5 6 7 4
  4 5 6 7 0 1 2 3
  5 6 7 4 3 0 1 2
  6 7 4 5 2 3 0 1
  7 4 5 6 1 2 3 0
have 80 intercalates.
.
For order N=10 pine Latin square
  0 1 2 3 4 5 6 7 8 9
  1 2 3 4 0 9 5 6 7 8
  2 3 4 0 1 8 9 5 6 7
  3 4 0 1 2 7 8 9 5 6
  4 0 1 2 3 6 7 8 9 5
  5 6 7 8 9 0 1 2 3 4
  6 7 8 9 5 4 0 1 2 3
  7 8 9 5 6 3 4 0 1 2
  8 9 5 6 7 2 3 4 0 1
  9 5 6 7 8 1 2 3 4 0
have 125 intercalates.
.
For order N=12 pine Latin square
  0 1 2 3 4 5 6 7 8 9 10 11
  1 2 3 4 5 0 11 6 7 8 9 10
  2 3 4 5 0 1 10 11 6 7 8 9
  3 4 5 0 1 2 9 10 11 6 7 8
  4 5 0 1 2 3 8 9 10 11 6 7
  5 0 1 2 3 4 7 8 9 10 11 6
  6 7 8 9 10 11 0 1 2 3 4 5
  7 8 9 10 11 6 5 0 1 2 3 4
  8 9 10 11 6 7 4 5 0 1 2 3
  9 10 11 6 7 8 3 4 5 0 1 2
  10 11 6 7 8 9 2 3 4 5 0 1
  11 6 7 8 9 10 1 2 3 4 5 0
have 252 intercalates.
		

Crossrefs

Formula

Hypothesis: For all known pine Latin squares of orders N=4k+2 number of intercalates a(n) = a(N/2)= a(2k+1) = (N/2)^3 = (2k+1)^3 = A016755((n-1)/2) (verified for N<29).
Hypothesis: For all known pine Latin squares of orders N=4k number of intercalates a(n) = a(N/2) = a(2k) = (N/2)^2 + (N/2)^3 = 4*k^2 + 8*k^3 = (2k)^2 * (2k+1) = 2*A089207(n/2) = 4*A099721(n/2) (verified for N<29).

A254473 24-hedral numbers: a(n) = (2*n + 1)*(8*n^2 + 14*n + 7).

Original entry on oeis.org

7, 87, 335, 847, 1719, 3047, 4927, 7455, 10727, 14839, 19887, 25967, 33175, 41607, 51359, 62527, 75207, 89495, 105487, 123279, 142967, 164647, 188415, 214367, 242599, 273207, 306287, 341935, 380247, 421319, 465247, 512127, 562055, 615127, 671439, 731087
Offset: 0

Views

Author

Luciano Ancora, Mar 26 2015

Keywords

Comments

This sequence is very close to the A046142 sequence: a(n) is asymptotic to A046142(n) as n tends to infinity.
The formula for A046142, the Haüy rhombic dodecahedral number, is remarkably similar, (2*n-1)*(8*n^2-14*n+7), where the first factor of the dodecahedral formula has "+1" versus "-1" in the 24-hedral formula, and the second factor of the former has "-14n" versus the latter of "+14n". Note that the rhombic dodecahedron has 24 faces, further explaining the relationship. The difference of these sequences is diff(n)=72*n^2 + 14. - Peter M. Chema, Jan 09 2016

Crossrefs

Programs

  • Magma
    [(2*n+1)*(8*n^2+14*n+7): n in [0..40]]; // Bruno Berselli, Mar 27 2015
  • Maple
    seq((2*n + 1)*(8*n^2 + 14*n + 7), n=0..100); # Robert Israel, Jan 11 2016
  • Mathematica
    Table[(2 n + 1) (8 n^2 + 14 n + 7), {n, 0, 40}] (* or *) LinearRecurrence[{4, -6, 4, -1}, {7, 87, 335, 847}, 40]
  • PARI
    vector(40, n, n--; (2*n+1)*(8*n^2+14*n+7)) \\ Bruno Berselli, Mar 27 2015
    
  • Sage
    [(2*n+1)*(8*n^2+14*n+7) for n in (0..40)] # Bruno Berselli, Mar 27 2015
    

Formula

G.f.: (7 + 59*x + 29*x^2 + x^3)/(1 - x)^4.
a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) - a(n-4).
a(n) = -A046142(-n) with A046142(0) = -7.
a(n) = 6*Sum_{k=0..n} (2*k+1)^2 + (2*n+1)^3. - Robert FERREOL, Nov 13 2023

A305290 Numbers k such that 4*k + 1 is a perfect cube, sorted by absolute values.

Original entry on oeis.org

0, -7, 31, -86, 182, -333, 549, -844, 1228, -1715, 2315, -3042, 3906, -4921, 6097, -7448, 8984, -10719, 12663, -14830, 17230, -19877, 22781, -25956, 29412, -33163, 37219, -41594, 46298, -51345, 56745, -62512, 68656, -75191, 82127, -89478, 97254, -105469, 114133, -123260, 132860
Offset: 1

Views

Author

Bruno Berselli, May 29 2018

Keywords

Crossrefs

Cf. A016755.
Cf. A000290: k such that 4*k is a square.
Cf. A002378: k such that 4*k+1 is a square.
Cf. A033431: k such that 4*k is a nonnegative cube.
Cf. A305291: k such that 4*k+3 is a cube.
Cf. A141046: k such that 4*k is a fourth power.
Cf. 4*A219086: k such that 4*k+1 is a fourth power.

Programs

  • Maple
    seq(coeff(series(x^2*(-7+10*x-7*x^2)/((1-x)*(1+x)^4), x,50),x,n),n=1..45); # Muniru A Asiru, May 31 2018
  • Mathematica
    LinearRecurrence[{-3, -2, 2, 3, 1}, {0, -7, 31, -86, 182}, 45] (* Jean-François Alcover, Jun 04 2018 *)
  • PARI
    concat(0, Vec(-x^2*(7 - 10*x + 7*x^2) / ((1 - x)*(1 + x)^4) + O(x^40))) \\ Colin Barker, Jun 04 2018

Formula

G.f.: x^2*(-7 + 10*x - 7*x^2)/((1 - x)*(1 + x)^4).
a(n) = -3*a(n-1) - 2*a(n-2) + 2*a(n-3) + 3*a(n-4) + a(n-5).
a(n) = (-1 - A016755(n-1)*(-1)^n)/4.
a(n) + a(-n) = (-1)^n*2^((1-(-1)^n)/2).
(n - 2)*(4*n^2 - 16*n + 19)*a(n) + (12*n^2 - 36*n + 31)*a(n-1) - (n - 1)*(4*n^2 - 8*n + 7)*a(n-2) = 0.
From Colin Barker, May 30 2018: (Start)
a(n) = n*(4*n^2 + 6*n + 3)/2 for n even.
a(n) = -(n + 1)*(4*n^2 + 2*n + 1)/2 for n odd.
(End)

A305291 Numbers k such that 4*k + 3 is a perfect cube, sorted by absolute values.

Original entry on oeis.org

-1, 6, -32, 85, -183, 332, -550, 843, -1229, 1714, -2316, 3041, -3907, 4920, -6098, 7447, -8985, 10718, -12664, 14829, -17231, 19876, -22782, 25955, -29413, 33162, -37220, 41593, -46299, 51344, -56746, 62511, -68657, 75190, -82128, 89477, -97255, 105468, -114134, 123259, -132861
Offset: 1

Views

Author

Bruno Berselli, May 29 2018

Keywords

Crossrefs

Programs

  • Maple
    seq(coeff(series(x*(-1+3*x-16*x^2+3*x^3-x^4)/((1-x)*(1+x)^4), x,50),x,n),n=1..45); # Muniru A Asiru, May 31 2018
  • Mathematica
    LinearRecurrence[{-3, -2, 2, 3, 1}, {-1, 6, -32, 85, -183}, 45] (* Jean-François Alcover, Jun 04 2018 *)
  • PARI
    Vec(-x*(1 - 3*x + 16*x^2 - 3*x^3 + x^4) / ((1 - x)*(1 + x)^4) + O(x^40)) \\ Colin Barker, Jun 04 2018

Formula

G.f.: x*(-1 + 3*x - 16*x^2 + 3*x^3 - x^4)/((1 - x)*(1 + x)^4).
a(n) = -3*a(n-1) - 2*a(n-2) + 2*a(n-3) + 3*a(n-4) + a(n-5).
a(n) = (-3 + A016755(n-1)*(-1)^n)/4.
a(n) = -A305290(n) - 1.
a(n) + a(-n) = 1 - 2^(1+(-1)^n).
(n - 2)*(4*n^2 - 16*n + 19)*a(n) + (12*n^2 - 36*n + 31)*a(n-1) - (n - 1)*(4*n^2 - 8*n + 7)*a(n-2) = 0.
From Colin Barker, May 30 2018: (Start)
a(n) = (4*n^3 - 6*n^2 + 3*n - 2)/2 for n even.
a(n) = -(4*n^3 - 6*n^2 + 3*n + 1)/2 for n odd.
(End)

A328408 G.f. A(x) satisfies: A(x) = A(x^2) + x * (1 + 4*x + x^2) / (1 - x)^4.

Original entry on oeis.org

1, 9, 27, 73, 125, 243, 343, 585, 729, 1125, 1331, 1971, 2197, 3087, 3375, 4681, 4913, 6561, 6859, 9125, 9261, 11979, 12167, 15795, 15625, 19773, 19683, 25039, 24389, 30375, 29791, 37449, 35937, 44217, 42875, 53217, 50653, 61731, 59319, 73125, 68921, 83349, 79507, 97163, 91125
Offset: 1

Views

Author

Ilya Gutkovskiy, Oct 14 2019

Keywords

Crossrefs

Programs

  • Magma
    [n eq 1 select 1 else IsOdd(n) select n^3 else Self(n div 2)+n^3 :n in [1..45]]; // Marius A. Burtea, Oct 15 2019
  • Mathematica
    nmax = 45; CoefficientList[Series[Sum[x^(2^k) (1 + 4 x^(2^k) + x^(2^(k + 1)))/(1 - x^(2^k))^4, {k, 0, Floor[Log[2, nmax]] + 1}], {x, 0, nmax}], x] // Rest
    a[n_] := If[EvenQ[n], a[n/2] + n^3, n^3]; Table[a[n], {n, 1, 45}]
    Table[DivisorSum[n, Boole[IntegerQ[Log[2, n/#]]] #^3 &], {n, 1, 45}]
    f[p_, e_] :=p^(3*e); f[2, e_] := (8^(e+1)-1)/7; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Oct 23 2023 *)

Formula

G.f.: Sum_{k>=0} x^(2^k) * (1 + 4*x^(2^k) + x^(2^(k+1))) / (1 - x^(2^k))^4.
G.f.: (1/7) * Sum_{k>=1} J_3(2*k) * x^k / (1 - x^k), where J_3() is the Jordan function (A059376).
Dirichlet g.f.: zeta(s-3) / (1 - 2^(-s)).
a(2*n) = a(n) + 8*n^3, a(2*n+1) = (2*n + 1)^3.
a(n) = Sum_{d|n} A209229(n/d) * d^3.
Product_{n>=1} (1 + x^n)^a(n) = g.f. for A023872.
Sum_{k=1..n} a(k) ~ 4*n^4/15. - Vaclav Kotesovec, Oct 15 2019
Multiplicative with a(2^e) = (8^(e+1)-1)/7, and a(p^e) = p^(3*e) for an odd prime p. - Amiram Eldar, Oct 23 2023

A371532 Centered cuboctahedral numbers: the number of integer triples (x,y,z) such that max(|x|,|y|,|z|) <= n and |x|+|y|+|z| <= 2n.

Original entry on oeis.org

1, 19, 93, 263, 569, 1051, 1749, 2703, 3953, 5539, 7501, 9879, 12713, 16043, 19909, 24351, 29409, 35123, 41533, 48679, 56601, 65339, 74933, 85423, 96849, 109251, 122669, 137143, 152713, 169419, 187301, 206399, 226753, 248403, 271389, 295751, 321529, 348763
Offset: 0

Views

Author

Peter Kagey, Mar 26 2024

Keywords

Examples

			The a(1) = 19 lattice points are all permutations of the points (0,0,0), (0,0,1), and (0,1,1), where any number of the coordinates can also be made negative (e.g., (1,-1,0)).
		

Crossrefs

Programs

  • Mathematica
    Array[(20*#^3 + 24*#^2 + 10*# + 3)/3 &, 50, 0] (* or *)
    LinearRecurrence[{4, -6, 4, -1}, {1, 19, 93, 263}, 50] (* Paolo Xausa, Apr 02 2024 *)
  • Python
    def A371532(n): return n*(n*(5*n+6<<2)+10)//3+1 # Chai Wah Wu, Apr 02 2024

Formula

a(n) = (20*n^3 + 24*n^2 + 10*n + 3)/3.
a(n) = A016755(n) - A130809(n-2).
G.f.: (x^3 + 23*x^2 + 15*x + 1)/(x-1)^4. - Paolo Xausa, Apr 02 2024
From Elmo R. Oliveira, Aug 22 2025: (Start)
E.g.f.: exp(x)*(3 + 54*x + 84*x^2 + 20*x^3)/3.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). (End)
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