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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A244879 Number of magic labelings of the cycle-of-loops graph LOOP X C_6 having magic sum n, where LOOP is the 1-vertex, 1-loop-edge graph.

Original entry on oeis.org

1, 18, 129, 571, 1884, 5103, 11998, 25362, 49347, 89848, 154935, 255333, 404950, 621453, 926892, 1348372, 1918773, 2677518, 3671389, 4955391, 6593664, 8660443, 11241066, 14433030, 18347095, 23108436, 28857843, 35752969, 43969626, 53703129, 65169688, 78607848
Offset: 0

Views

Author

N. J. A. Sloane, Jul 08 2014

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(1 + 11 x + 24 x^2 + 11 x^3 + x^4)/(1 - x)^7, {x, 0, 31}], x] (* Michael De Vlieger, Sep 15 2017 *)
    LinearRecurrence[{7,-21,35,-35,21,-7,1},{1,18,129,571,1884,5103,11998},40] (* Harvey P. Dale, Jul 30 2019 *)
  • PARI
    Vec((1 + 11*x + 24*x^2 + 11*x^3 + x^4) / (1 - x)^7 + O(x^40)) \\ Colin Barker, Jan 11 2017

Formula

G.f.: (1 + 11*x + 24*x^2 + 11*x^3 + x^4) / (1 - x)^7.
From Colin Barker, Jan 11 2017: (Start)
a(n) = (120 + 438*n + 677*n^2 + 570*n^3 + 275*n^4 + 72*n^5 + 8*n^6) / 120.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n > 6.
(End)

Extensions

Name corrected by David J. Seal, Sep 13 2017

A061927 a(n) = n*(n+1)*(2*n+1)*(n^2+n+3)/30.

Original entry on oeis.org

0, 1, 9, 42, 138, 363, 819, 1652, 3060, 5301, 8701, 13662, 20670, 30303, 43239, 60264, 82280, 110313, 145521, 189202, 242802, 307923, 386331, 479964, 590940, 721565, 874341, 1051974, 1257382, 1493703, 1764303, 2072784, 2422992, 2819025
Offset: 0

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Author

Henry Bottomley, May 17 2001

Keywords

Comments

Also number of magic labelings of the cubical graph of magic sum n-1 [Ahmed]. - R. J. Mathar, Jan 25 2007
If Y_i (i=1,2,3) are 2-blocks of a (n+3)-set X then a(n-4) is the number of 8-subsets of X intersecting each Y_i (i=1,2,3). - Milan Janjic, Oct 28 2007
The cube graph is also the prism graph I X C_4, so this is related to the number of magic labelings of other prism & related graphs. - David J. Seal, Sep 13 2017

Crossrefs

Cf. A006325, A019298, A244497, A244873, A289992, A292281, partial sums of A014820, A006975 (binomial transform shifted left).

Programs

  • Mathematica
    Table[n (n + 1) (2 n + 1) (n^2 + n + 3)/30, {n, 0, 33}] (* or *)
    CoefficientList[Series[x (1 + x)^3/(-1 + x)^6, {x, 0, 33}], x] (* Michael De Vlieger, Sep 15 2017 *)
    LinearRecurrence[{6,-15,20,-15,6,-1},{0,1,9,42,138,363},40] (* Harvey P. Dale, Apr 18 2018 *)
  • PARI
    a(n) = { n*(n + 1)*(2*n + 1)*(n^2 + n + 3)/30 } \\ Harry J. Smith, Jul 29 2009

Formula

a(n) = a(n-1) + A014820(n) = A061926(9, n).
G.f.: x*(1+x)^3/(-1+x)^6 = 20/(-1+x)^5 + 1/(-1+x)^2 + 7/(-1+x)^3 + 18/(-1+x)^4 + 8/(-1+x)^6. - R. J. Mathar, Nov 18 2007

A244880 Number of magic labelings of the cycle-of-loops graph LOOP X C_8 having magic sum n, where LOOP is the 1-vertex, 1-loop-edge graph.

Original entry on oeis.org

1, 47, 650, 4726, 23219, 87677, 274132, 743724, 1806597, 4016683, 8306078, 16168802, 29904823, 52936313, 90209192, 148694104, 238002057, 371131047, 565361074, 843316046, 1234212155, 1775313397, 2513615996, 3507784580, 4830364045, 6570292131, 8835738822, 11757299770, 15491572031
Offset: 0

Views

Author

N. J. A. Sloane, Jul 08 2014

Keywords

Crossrefs

Programs

  • Maple
    A244880:=n->(630 + 3051*n + 6570*n^2 + 8211*n^3 + 6503*n^4 + 3339*n^5 + 1085*n^6 + 204*n^7 + 17*n^8) / 630: seq(A244880(n), n=0..50); # Wesley Ivan Hurt, Sep 16 2017
  • Mathematica
    CoefficientList[Series[(1 + 38 (x + x^5) + 263 (x^2 + x^4) + 484 x^3 + x^6)/(1 - x)^9, {x, 0, 28}], x] (* Michael De Vlieger, Sep 15 2017 *)
  • PARI
    Vec((1 + 6*x + x^2)*(1 + 32*x + 70*x^2 + 32*x^3 + x^4) / (1 - x)^9 + O(x^30)) \\ Colin Barker, Jan 12 2017

Formula

G.f.: (1+38*(x+x^5)+263*(x^2+x^4)+484*x^3+x^6) / (1-x)^9.
From Colin Barker, Jan 12 2017: (Start)
a(n) = (630 + 3051*n + 6570*n^2 + 8211*n^3 + 6503*n^4 + 3339*n^5 + 1085*n^6 + 204*n^7 + 17*n^8) / 630.
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>8.
(End)
(326*n^2-195*n+142)*a(n) +(-652*n^2-652*n-10725)*a(n-1) +(326*n^2+847*n+663)*a(n-2) +2*(-165*n^2-165*n-71)=0. - R. J. Mathar, Mar 10 2025

Extensions

Name corrected by David J. Seal, Sep 13 2017

A085461 Number of 5-tuples (v1,v2,v3,v4,v5) of nonnegative integers less than n such that v1 <= v5, v2 <= v5, v2 <= v4 and v3 <= v4.

Original entry on oeis.org

1, 13, 70, 246, 671, 1547, 3164, 5916, 10317, 17017, 26818, 40690, 59787, 85463, 119288, 163064, 218841, 288933, 375934, 482734, 612535, 768867, 955604, 1176980, 1437605, 1742481, 2097018, 2507050, 2978851, 3519151, 4135152, 4834544
Offset: 1

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Author

Goran Kilibarda, Vladeta Jovovic, Jul 01 2003

Keywords

Comments

Number of monotone n-weightings of a certain connected bipartite digraph. A monotone n-(vertex) weighting of a digraph D=(V,E) is a function w: V -> {0,1,...,n-1} such that w(v1) <= w(v2) for every arc (v1,v2) from E.
Kekulé numbers for certain benzenoids. - Emeric Deutsch, Nov 18 2005
Can be constructed by taking the product of the three members of a Pythagorean triples and dividing by 60. Formula: n*(n^2-1)*(n^2+1)/240 where n runs through the odd numbers >= 3. - Pierre Gayet, Apr 04 2009
Number of composable morphisms in a height-n tower of retractions. A retraction between objects X and Y is a pair of maps s:X->Y and r:Y->X such that r(s(x))=x for all x in X. Given objects X_0,X_1,X_2,...,X_n, we can ask for retractions s_i:X_i->X_{i+1},r_i:X_{i+1}->X_i, for each 0 <= i < n. The total number of morphisms in that category is 0^2 + 1^2 + 2^2 + ... + n^2 (cf. A000330). The total number of composable pairs of morphisms in that category is the sequence given here. - David Spivak, Feb 26 2014

References

  • S. J. Cyvin and I. Gutman, KekulĂ© structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 168).

Crossrefs

Programs

  • Mathematica
    Rest[CoefficientList[Series[x*(1 + x)*(1 + 6*x + x^2)/(1 - x)^6, {x, 0, 50}], x]] (* G. C. Greubel, Oct 06 2017 *)
  • PARI
    x='x+O('x^50); Vec(x*(1+x)*(1+6*x+x^2)/(1-x)^6) \\ G. C. Greubel, Oct 06 2017

Formula

a(n) = n + 11*binomial(n, 2) + 34*binomial(n, 3) + 40*binomial(n, 4) + 16*binomial(n, 5) = 1/30*n*(n+1)*(2*n+1)*(2*n^2 + 2*n + 1).
From Bruno Berselli, Dec 27 2010: (Start)
G.f.: x*(1+x)*(1+6*x+x^2)/(1-x)^6.
a(n) = ( n*A110450(n) - Sum_{i=0..n-1} A110450(i) )/3. (End)

A244869 Number of magic labelings with magic sum n of first graph shown in link.

Original entry on oeis.org

1, 9, 43, 143, 379, 859, 1738, 3226, 5597, 9197, 14453, 21881, 32095, 45815, 63876, 87236, 116985, 154353, 200719, 257619, 326755, 410003, 509422, 627262, 765973, 928213, 1116857, 1335005, 1585991, 1873391, 2201032, 2573000, 2993649, 3467609, 3999795, 4595415, 5259979, 5999307, 6819538
Offset: 0

Views

Author

N. J. A. Sloane, Jul 08 2014

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{5,-9,5,5,-9,5,-1},{1,9,43,143,379,859,1738},50] (* Paolo Xausa, Dec 06 2023 *)
  • PARI
    Vec((1+4*x+7*x^2+4*x^3+x^4) / ((1-x)^6*(1+x)) + O(x^40)) \\ Colin Barker, Jan 11 2017

Formula

G.f.: (1 + 4*x + 7*x^2 + 4*x^3 + x^4) / ((1 - x)^6*(1 + x)).
From Colin Barker, Jan 11 2017: (Start)
a(n) = (15*(63 + (-1)^n) + 2592*n + 2880*n^2 + 1660*n^3 + 510*n^4 + 68*n^5) / 960.
a(n) = 5*a(n-1) - 9*a(n-2) + 5*a(n-3) + 5*a(n-4) - 9*a(n-5) + 5*a(n-6) - a(n-7) for n>6.
(End)

A244876 Number of magic labelings with magic sum n of 8th graph shown in link.

Original entry on oeis.org

1, 18, 154, 813, 3157, 9880, 26429, 62713, 135470, 271285, 510485, 911840, 1558368, 2564093, 4082142, 6313934, 9519951, 14031732, 20265700, 28738335, 40083439, 55070862, 74627587, 99860383, 132081092, 172833583, 223923623, 287450506, 365841890, 461890475, 578794188
Offset: 0

Views

Author

N. J. A. Sloane, Jul 08 2014

Keywords

Crossrefs

Programs

  • Mathematica
    Table[3 n^7/160 + 63 n^6/320 + 151 n^5/160 + 339 n^4/128 + 2251 n^3/480 + n^2 (-1)^n/64 + 1677 n^2/320 + 3 n (-1)^n/64 + 3259 n/960 + 9 (-1)^n/256 + 247/256, {n,0,30}] (* Bruno Berselli, Jul 08 2014 *)

Formula

G.f.: (1+13*x+71*x^2+174*x^3+238*x^4+174*x^5+71*x^6+13*x^7+x^8)/((1-x)^8*(1+x)^3).
a(n) = 3*n^7/160 + 63*n^6/320 + 151*n^5/160 + 339*n^4/128 + 2251*n^3/480 + n^2*(-1)^n/64 + 1677*n^2/320 + 3*n*(-1)^n/64 + 3259*n/960 + 9*(-1)^n/256 + 247/256. [Bruno Berselli, Jul 08 2014]

A289992 Number of magic labelings of the prism graph I X C_8 having magic sum n.

Original entry on oeis.org

1, 49, 746, 6122, 34067, 144963, 506772, 1524628, 4074949, 9898229, 22220990, 46695870, 92769495, 175610631, 318756136, 557659432, 944355593, 1553488697, 2489980818, 3898657938, 5976186139, 8985711691, 13274641084, 19296041660, 27634190285
Offset: 0

Views

Author

David J. Seal, Sep 13 2017

Keywords

Crossrefs

Formula

a(n) = A244880(n) + 2*Sum_{i=0..n-1} A244880(i).
From Colin Barker, Sep 13 2017: (Start)
G.f.: (1 + x)*(1 + 6*x + x^2)*(1 + 32*x + 70*x^2 + 32*x^3 + x^4) / (1 - x)^10.
a(n) = 10*a(n-1) - 45*a(n-2) + 120*a(n-3) - 210*a(n-4) + 252*a(n-5) - 210*a(n-6) + 120*a(n-7) - 45*a(n-8) + 10*a(n-9) - a(n-10) for n>9. (End)
[Proof of the g.f. follows from the convolution formula and insertion of the g.f. A244880(x): Sum_{n>=0} a(n)x^n = Sum_{n>=0} A244880(n)*x^n +2*Sum_{n>=0} Sum_{i=0..n-1} A244880(i)*x^n = A244880(x) +2*Sum_{i>=0} Sum_{n>=i+1} A244880(i)*x^n = A244880(x) +2*Sum_{i>=0} A244880(i)*x^(i+1) Sum_{n>=0} x^n = A244880(x)+2*A244880(x)*x/(1+x) = A244880(x)*(1+2*x/(1-x)). R. J. Mathar, Mar 09 2025]

A292281 Number of magic labelings of the prism graph I X C_6 having magic sum n.

Original entry on oeis.org

1, 20, 167, 867, 3322, 10309, 27410, 64770, 139479, 278674, 523457, 933725, 1594008, 2620411, 4168756, 6444020, 9711165, 14307456, 20656363, 29283143, 40832198, 56086305, 75987814, 101661910, 134442035, 175897566, 227863845, 292474657, 372197252, 469870007, 588742824
Offset: 0

Views

Author

David J. Seal, Sep 13 2017

Keywords

Crossrefs

Programs

  • Mathematica
    f[n_] := SeriesCoefficient[(1 + 11 x + 24 x^2 + 11 x^3 + x^4)/(1 - x)^7, {x, 0, n}]; Table[f[n] + 2 Sum[f[i], {i, 0, n - 1}], {n, 0, 24}] (* Michael De Vlieger, Sep 15 2017 *)

Formula

a(n) = A244879(n) + 2*Sum_{i=0..n-1} A244879(i).
From Colin Barker, Sep 13 2017: (Start)
G.f.: (1 + x)*(1 + 11*x + 24*x^2 + 11*x^3 + x^4) / (1 - x)^8.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>7.
(End)
[Proof of the g.f. follows from the g.f. of A244879 with the resummation demonstrated in A289992: g.f. = A244879(x)*(1+2*x/(1-x)). - R. J. Mathar, Mar 09 2025]

A053494 Number of symmetric 5 X 5 matrices of nonnegative integers with every row and column adding to n.

Original entry on oeis.org

1, 26, 348, 2698, 14751, 62781, 222190, 681460, 1865715, 4655535, 10756921, 23290026, 47700173, 93104473, 174248451, 314246511, 548380980, 929209095, 1533389605, 2470568045, 3894914166, 6019752376, 9136114923, 13635769173, 20039850376, 29033765566
Offset: 0

Views

Author

N. J. A. Sloane, Jan 15 2000

Keywords

References

  • R. P. Stanley, Enumerative Combinatorics, Wadsworth, Vol. 1, 1986; see Prop. 4.6.21, p. 235, G_5(lambda).

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(1+21x+222x^2+1082x^3+3133x^4+5722x^5+7013x^6+5722x^7+3133x^8+1082x^9+222x^10+21x^11+x^12)/((1-x)^11(1+x)^6),{x,0,30}],x] (* or *) LinearRecurrence[ {5,-4,-20,40,16,-100,44,110,-110,-44,100,-16,-40,20,4,-5,1},{1,26,348,2698,14751,62781,222190,681460,1865715,4655535,10756921,23290026,47700173,93104473,174248451,314246511,548380980},30] (* Harvey P. Dale, Mar 05 2023 *)
  • PARI
    Vec((1 + 21*x + 222*x^2 + 1082*x^3 + 3133*x^4 + 5722*x^5 + 7013*x^6 + 5722*x^7 + 3133*x^8 + 1082*x^9 + 222*x^10 + 21*x^11 + x^12) / ((1 - x)^11*(1 + x)^6) + O(x^30)) \\ Colin Barker, Jan 14 2017

Formula

G.f.: (1 + 21*x + 222*x^2 + 1082*x^3 + 3133*x^4 + 5722*x^5 + 7013*x^6 + 5722*x^7 + 3133*x^8 + 1082*x^9 + 222*x^10 + 21*x^11 + x^12) / ((1-x)^11*(1+x)^6).
a(n) = (189*(59981+5555*(-1)^n) + 18*(2345165+65331*(-1)^n)*n + (76615494+689850*(-1)^n)*n^2 + 40*(2138179+6237*(-1)^n)*n^3 + (63277966+47250*(-1)^n)*n^4 + 1260*(25421+3*(-1)^n)*n^5 + 11171664*n^6 + 2644080*n^7 + 405954*n^8 + 36500*n^9 + 1460*n^10) / 12386304. - Colin Barker, Jan 14 2017

Extensions

Revised definition, Jul 06 2014

A244881 Expansion of (1 + 26*x + 109*x^2 + 109*x^3 + 26*x^4 + x^5) / (1 - x)^8.

Original entry on oeis.org

1, 34, 353, 2037, 8272, 26585, 72302, 173502, 377739, 760804, 1437799, 2576795, 4415346, 7280131, 11609996, 17982668, 27145413, 40049910, 57891613, 82153873, 114657092, 157613181, 213685594, 286055210, 378492335, 495435096, 642074499, 824446423, 1049530822
Offset: 0

Views

Author

N. J. A. Sloane, Jul 08 2014

Keywords

Programs

  • PARI
    Vec((1 + x)*(1 + 25*x + 84*x^2 + 25*x^3 + x^4) / (1 - x)^8 + O(x^30)) \\ Colin Barker, Jan 12 2017

Formula

From Colin Barker, Jan 12 2017: (Start)
a(n) = (2520 + 11526*n + 22617*n^2 + 24724*n^3 + 16275*n^4 + 6454*n^5 + 1428*n^6 + 136*n^7) / 2520.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>7.
(End)
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