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.

Showing 1-10 of 12 results. Next

A083200 Polynexus numbers of order 7.

Original entry on oeis.org

0, 1, 17, 118, 514, 1681, 4529, 10612, 22380, 43473, 79057, 136202, 224302, 355537, 545377, 813128, 1182520, 1682337, 2347089, 3217726, 4342394, 5777233, 7587217, 9847036, 12642020, 16069105, 20237841, 25271442, 31307878, 38501009, 47021761, 57059344, 68822512
Offset: 1

Views

Author

Xavier Acloque, Jun 01 2003

Keywords

Crossrefs

Cf. A079547, A088889-A088894 (similar sequences).

Programs

  • Mathematica
    Table[((n^7 - (n - 1)^7) - (n^3 - (n - 1)^3))/120, {n, 31}] (* Bruno Berselli, Feb 13 2012 *)

Formula

a(n) = ((n^7-(n-1)^7)-(n^3-(n-1)^3))/120.
G.f.: x^2*(1+10*x+20*x^2+10*x^3+x^4)/(1-x)^7. - Bruno Berselli, Feb 13 2012

Extensions

More terms from David Wasserman, Oct 26 2004
Offset changed (according to the formula) from Bruno Berselli, Feb 13 2012

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

Views

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, Kekulé 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)

A088889 Polynexus numbers of order 8.

Original entry on oeis.org

0, 1, 26, 245, 1353, 5368, 17017, 45878, 109446, 237291, 476476, 898403, 1607255, 2750202, 4529539, 7216924, 11169884, 16850757, 24848238, 35901697, 50928437, 71054060, 97646109, 132351154, 177135490, 234329615, 306676656, 397384911, 510184675, 649389518
Offset: 1

Views

Author

Xavier Acloque, Oct 21 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((n^8 - (n - 1)^8) - (n^4 - (n - 1)^4))/240, {n, 26}] (* Bruno Berselli, Feb 10 2012 *)
    LinearRecurrence[{8,-28,56,-70,56,-28,8,-1},{0,1,26,245,1353,5368,17017,45878},30] (* Harvey P. Dale, Oct 31 2024 *)

Formula

a(n) = ((n^8-(n-1)^8)-(n^4-(n-1)^4))/240 = ((n^8-(n-1)^8)-(n^4-(n-1)^4))/(2^8-2^4).
G.f.: x^2*(1+x)*(1+17*x+48*x^2+17*x^3+x^4)/(1-x)^8. - Bruno Berselli, Feb 10 2012

Extensions

First term added according to the formula from Bruno Berselli, Feb 10 2012

A088894 Polynexus numbers of order 16.

Original entry on oeis.org

0, 1, 656, 64895, 2263323, 40728358, 464160877, 3788798018, 23985732786, 124343403711, 548683300726, 2120490369833, 7334132330405, 23085114905772, 67009386720139, 181293280189204, 461148470725844, 1110780513139917, 2548868780082828, 5600100525524707
Offset: 1

Views

Author

Xavier Acloque, Oct 21 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((n^16 - (n - 1)^16) - (n^4 - (n - 1)^4))/65520, {n, 20}] (* Bruno Berselli, Feb 08 2012 *)

Formula

a(n) = ((n^16-(n-1)^16)-(n^4-(n-1)^4))/65520 = ((n^16-(n-1)^16)-(n^4-(n-1)^4))/(2^16-2^4).
G.f.: x^2*(1+x)*(1+639*x+53880*x^2+1249283*x^3+10687767*x^4+38266494*x^5+59151072*x^6+38266494*x^7+10687767*x^8+1249283*x^9+53880*x^10+639*x^11+x^12)/(1-x)^16. - Bruno Berselli, Feb 08 2012

Extensions

First term added according to the formula from Bruno Berselli, Feb 08 2012

A085465 Number of monotone n-weightings of complete bipartite digraph K(3,3).

Original entry on oeis.org

1, 15, 102, 442, 1443, 3885, 9100, 19188, 37269, 67771, 116754, 192270, 304759, 467481, 696984, 1013608, 1442025, 2011815, 2758078, 3722082, 4951947, 6503365, 8440356, 10836060, 13773565, 17346771, 21661290, 26835382, 33000927, 40304433
Offset: 1

Views

Author

Goran Kilibarda, Vladeta Jovovic, Jul 01 2003

Keywords

Comments

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.
a(n) = number of proper mergings of a 3-antichain and an (n-1)-chain. - Henri Mühle, Aug 17 2012

Crossrefs

Programs

  • Magma
    [1/20*n*(n+1)*(n^2+1)*(n^2+2*n+2): n in [1..40]]; // Vincenzo Librandi, Oct 06 2017
  • Mathematica
    Rest[CoefficientList[Series[x*(1 + 4*x + x^2)^2/(1 - x)^7, {x, 0, 50}], x]] (* G. C. Greubel, Oct 06 2017 *)
    LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {1, 15, 102, 442, 1443, 3885, 9100}, 40] (* Vincenzo Librandi, Oct 06 2017 *)
  • PARI
    x='x+O('x^50); Vec(x*(1+4*x+x^2)^2/(1-x)^7) \\ G. C. Greubel, Oct 06 2017
    

Formula

a(n) = n + 13*binomial(n, 2) + 60*binomial(n, 3) + 120*binomial(n, 4) + 108*binomial(n, 5) + 36*binomial(n, 6) = 1/20*n*(n+1)*(n^2+1)*(n^2+2*n+2) = Sum_{i=1..n} ((n+1-i)^3-(n-i)^3)*i^3. More generally, number of monotone n-weightings of complete bipartite digraph K(s, t) is Sum_{i=1..n} ((n+1-i)^s-(n-i)^s)*i^t = Sum_{i=1..n} ((n+1-i)^t-(n-i)^t)*i^s.
G.f.: x*(1+4*x+x^2)^2/(1-x)^7. - Colin Barker, Apr 01 2012
a(n) = A006003(n)*A006003(n+1)/5 for n>0. - Bruno Berselli, Jun 26 2018

A088890 Polynexus numbers of order 8.

Original entry on oeis.org

0, 1, 25, 234, 1290, 5115, 16211, 43700, 104244, 226005, 453805, 855646, 1530750, 2619279, 4313895, 6873320, 10638056, 16048425, 23665089, 34192210, 48503410, 67670691, 92996475, 126048924, 168700700, 223171325, 292073301, 378462150, 485890534, 618466615
Offset: 1

Views

Author

Xavier Acloque, Oct 21 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((n^8 - (n - 1)^8) - (n^2 - (n - 1)^2))/252, {n, 26}] (* Bruno Berselli, Feb 10 2012 *)
    LinearRecurrence[{8,-28,56,-70,56,-28,8,-1},{0,1,25,234,1290,5115,16211,43700},30] (* Harvey P. Dale, Nov 24 2019 *)

Formula

a(n) = ((n^8-(n-1)^8)-(n^2-(n-1)^2))/252 = ((n^8-(n-1)^8)-(n^2-(n-1)^2))/(2^8-2^2).
G.f.: x^2*(1+x)*(1+16*x+46*x^2+16*x^3+x^4)/(1-x)^8. - Bruno Berselli, Feb 10 2012

Extensions

First term added according to the formula from Bruno Berselli, Feb 10 2012

A088891 Polynexus numbers of order 9.

Original entry on oeis.org

0, 1, 38, 481, 3355, 16120, 60071, 186238, 502386, 1215435, 2694340, 5559191, 10803013, 19953466, 35282365, 60071660, 98945236, 158276613, 246683346, 375619645, 560079455, 819422956, 1178340163, 1667966026, 2327162150, 3203980975, 4357328976, 5858846163
Offset: 1

Views

Author

Xavier Acloque, Oct 21 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((n^9-(n-1)^9)-(n^3-(n-1)^3))/504,{n,30}] (* or *) LinearRecurrence[ {9,-36,84,-126,126,-84,36,-9,1},{0,1,38,481,3355,16120,60071,186238,502386},30] (* Harvey P. Dale, Jan 18 2012 *)

Formula

a(n) = ((n^9-(n-1)^9)-(n^3-(n-1)^3))/504 = ((n^9-(n-1)^9)-(n^3-(n-1)^3))/(2^9-2^3).
a(1)=1, a(2)=38, a(3)=481, a(4)=3355, a(5)=16120, a(6)=60071, a(7)=186238, a(8)=502386, a(9)=1215435, 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). - Harvey P. Dale, Jan 18 2012
G.f.: x^2*(1+29*x+175*x^2+310*x^3+175*x^4+29*x^5+x^6)/(1-x)^9. - Bruno Berselli, Feb 10 2012

Extensions

Offset changed and first term added (according to the formula) from Bruno Berselli, Feb 08 2012

A088892 Polynexus numbers of order 14.

Original entry on oeis.org

0, 1, 291, 16096, 356232, 4411517, 36621423, 227095448, 1128128568, 4708376529, 17078744419, 55199550120, 161993768080, 438011626365, 1103841220991, 2616890599056, 5880356075792, 12602902382337, 25897027973187, 51245013077968, 98017089897528, 181801058663389
Offset: 1

Views

Author

Xavier Acloque, Oct 21 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((n^14 - (n - 1)^14) - (n^2 - (n - 1)^2))/16380, {n, 20}] (* Bruno Berselli, Feb 08 2012 *)
    LinearRecurrence[{14,-91,364,-1001,2002,-3003,3432,-3003,2002,-1001,364,-91,14,-1},{0,1,291,16096,356232,4411517,36621423,227095448,1128128568,4708376529,17078744419,55199550120,161993768080,438011626365},20] (* Harvey P. Dale, Mar 04 2024 *)

Formula

a(n) = ((n^14-(n-1)^14)-(n^2-(n-1)^2))/16380 = ((n^14-(n-1)^14)-(n^2-(n-1)^2))/(2^14-2^2).
G.f.: x^2*(1+x)*(1+276*x+11837*x^2+145168*x^3+638914*x^4+1068728*x^5+638914*x^6+145168*x^7+11837*x^8+276*x^9+x^10)/(1-x)^14. - Bruno Berselli, Feb 08 2012

Extensions

First term added according to the formula from Bruno Berselli, Feb 08 2012

A088893 Polynexus numbers of order 15.

Original entry on oeis.org

0, 1, 437, 32338, 898774, 13420861, 130567049, 929084572, 5210829060, 24240197433, 96985597357, 342789175982, 1092151142842, 3186269918917, 8618003504977, 21826239750488, 52182586901800, 118565859736497, 257462955231909, 536839834252906, 1079191653936254
Offset: 1

Views

Author

Xavier Acloque, Oct 21 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((n^15 - (n - 1)^15) - (n^3 - (n - 1)^3))/32760, {n, 20}] (* Bruno Berselli, Feb 08 2012 *)

Formula

a(n) = ((n^15-(n-1)^15)-(n^3-(n-1)^3))/32760 = ((n^15-(n-1)^15)-(n^3-(n-1)^3))/(2^15-2^3).
G.f.: x^2*(1+422*x+25888*x^2+459134*x^3+3137271*x^4+9505116*x^5+13661136*x^6+9505116*x^7+3137271*x^8+459134*x^9+25888*x^10+422*x^11+x^12)/(1-x)^15. - Bruno Berselli, Feb 08 2012

Extensions

First term added according to the formula from Bruno Berselli, Feb 08 2012

A085462 Number of 5-tuples (v1,v2,v3,v4,v5) of nonnegative integers less than n such that v1<=v4, v1<=v5, v2<=v4 and v3<=v4.

Original entry on oeis.org

1, 14, 77, 273, 748, 1729, 3542, 6630, 11571, 19096, 30107, 45695, 67158, 96019, 134044, 183260, 245973, 324786, 422617, 542717, 688688, 864501, 1074514, 1323490, 1616615, 1959516, 2358279, 2819467, 3350138, 3957863, 4650744
Offset: 1

Views

Author

Goran Kilibarda and 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.
Dimensions of certain Lie algebra (see Landsberg-Manivel reference for precise definition). - N. J. A. Sloane, Oct 15 2007

Crossrefs

Programs

  • Magma
    [n*(n+1)*(2*n+1)*(3*n+1)*(3*n+2)/120: n in [0..50]]; // G. C. Greubel, Oct 07 2017
  • Mathematica
    Rest[CoefficientList[Series[x*(1 + x)*(1 + 7*x + x^2)/(1 - x)^6, {x, 0, 50}], x]] (* or *) Table[n*(n+1)*(2*n+1)*(3*n+1)*(3*n+2)/120, {n,0,50}] (* G. C. Greubel, Oct 07 2017 *)
  • PARI
    x='x+O('x^50); Vec(x*(1+x)*(1+7*x+x^2)/(1-x)^6) \\ G. C. Greubel, Oct 07 2017
    

Formula

a(n) = n + 12*binomial(n, 2) + 38*binomial(n, 3) + 45*binomial(n, 4) + 18*binomial(n, 5).
a(n) = n*(n+1)*(2*n+1)*(3*n+1)*(3*n+2)/120.
G.f.: x*(1+x)*(1+7*x+x^2)/(1-x)^6. - Colin Barker, Apr 01 2012
a(n) = sum(i=1..n, sum(j=1..n, i^2 * Min(i,j))). - Enrique Pérez Herrero, Jan 30 2013
Showing 1-10 of 12 results. Next