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 11 results. Next

A072474 Sum of next n squares.

Original entry on oeis.org

1, 13, 77, 294, 855, 2071, 4403, 8492, 15189, 25585, 41041, 63218, 94107, 136059, 191815, 264536, 357833, 475797, 623029, 804670, 1026431, 1294623, 1616187, 1998724, 2450525, 2980601, 3598713, 4315402, 5142019, 6090755, 7174671, 8407728, 9804817, 11381789, 13155485
Offset: 1

Views

Author

Amarnath Murthy, Jun 20 2002

Keywords

Examples

			a(1) = 1^2 = 1;
a(2) = 2^2 + 3^2 = 13;
a(3) = 4^2 + 5^2 + 6^2 = 77.
		

Crossrefs

Cf. A006003 (for natural numbers), A260513 (for triangular numbers), A372583 (for pentagonal numbers), A372751 (for hexagonal numbers), A075664 (for cubes).

Programs

  • Magma
    [n*(3*n^2+1)*(n^2+2)/12: n in [1..35]]; // Vincenzo Librandi, Dec 31 2024
  • Mathematica
    Table[Sum[ i^2, {i, n(n - 1)/2 + 1, n(n + 1)/2}], {n, 1, 35}]
  • PARI
    a(n) = n*(3*n^2+1)*(n^2+2)/12
    

Formula

a(n) = k*(k+1)*(2*k+1)/6 - r*(r+1)*(2*r+1)/6, where k = n*(n+1)/2 and r = n*(n-1)/2.
a(n) = A000330(n*(n+1)/2) - A000330(n*(n-1)/2).
a(n) = (n/12)*(3*n^2 + 1)*(n^2 + 2). - Benoit Cloitre, Jun 26 2002
G.f.: x*(1+3*x+x^2)*(1+4*x+x^2)/(1-x)^6. - Colin Barker, Mar 23 2012
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n > 6. - Jinyuan Wang, May 25 2020
E.g.f.: exp(x)*x*(12 + 66*x + 82*x^2 + 30*x^3 + 3*x^4)/12. - Stefano Spezia, May 14 2024

Extensions

Edited by Robert G. Wilson v, Jun 21 2002

A069876 a(n) = (k-n+1)^n + (k-n+2)^n + ... + (k-1)^n + k^n, where k = n(n+1)/2.

Original entry on oeis.org

1, 13, 405, 23058, 2078375, 271739011, 48574262275, 11373936899396, 3377498614484589, 1240006139651007925, 551449374186192949841, 292093390490112799117190, 181694111127303339553250275, 131144830297438122797495823519, 108709456000518111261404495694375
Offset: 1

Views

Author

Amarnath Murthy, Apr 25 2002

Keywords

Comments

Sum of next n n-th powers.

Examples

			a(1) = 1^1 = 1; a(2) = 2^2 + 3^2 = 13; a(3) = 4^3 + 5^3 + 6^3 = 405; a(4) = 7^4 + 8^4 + 9^4 + 10^4 = 23058.
		

Crossrefs

Cf. A072474 (for squares), A075664 - A075671 (3rd to 10th powers).

Programs

  • Mathematica
    i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; Table[Sum[i^n, {i, i1, i2}], {n, 20}]
  • Python
    def A069876(n): return sum(((n*(n+1)>>1)-i)**n for i in range(n)) # Chai Wah Wu, Feb 10 2025

Extensions

More terms from Larry Reeves (larryr(AT)acm.org) and Zak Seidov, Sep 24 2002

A075671 Sum of next n 10th powers.

Original entry on oeis.org

1, 60073, 71280377, 14843001474, 1091618326275, 39736919990851, 870012241054523, 12967387960026452, 143075291905145949, 1240006139651007925, 8817026830146599701, 53151169903167142598, 278615540073819826527, 1295610629596485350799, 5430916505417064431575
Offset: 1

Views

Author

Zak Seidov, Sep 24 2002

Keywords

Examples

			a(1) = 1^10 = 1; a(2) = 2^10 + 3^10 = 60073; a(3) = 4^10 + 5^10 + 6^10 = 71280377; a(4) = 7^10 + 8^10 + 9^10 + 10^10 = 14843001474.
		

Crossrefs

Cf. A008454 (10th powers).
Cf. A072474 (for squares), A075664 - A075670 (3rd to 9th powers), A069876 (n-th powers).

Programs

  • Mathematica
    i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=10; Table[Sum[i^s, {i, i1, i2}], {n, 20}]
    With[{nn=20},Total/@TakeList[Range[(nn(nn+1))/2]^10,Range[nn]]] (* Requires Mathematica version 11 or later *) (* Harvey P. Dale, Mar 18 2018 *)

Formula

a(n) = Sum_{i=n(n-1)/2+1..n(n-1)/2+n} i^10.
a(n) = (33n^21 + 825n^19 + 6336n^17 + 18546n^15 + 14289n^13 - 14187n^11 - 418n^9 + 20592n^7 - 10560n^5 - 4224n^3 + 2560n)/33792. - Charles R Greathouse IV, Sep 17 2009
G.f.: (x^20 +60051*x^19 +69959002*x^18 +13288708503*x^17 +781445555829*x^16 +19040717780376*x^15 +225625446425352*x^14 +1431958892640624*x^13 +5170348336132746*x^12 +11021721646301518*x^11 +14154518527431996*x^10 +11021721646301518*x^9 +5170348336132746*x^8 +1431958892640624*x^7 +225625446425352*x^6 +19040717780376*x^5 +781445555829*x^4 +13288708503*x^3 +69959002*x^2 +60051*x +1) / (x -1)^22. - Colin Barker, Dec 19 2012

Extensions

More terms from Colin Barker, Dec 19 2012

A075665 Sum of next n 4th powers.

Original entry on oeis.org

1, 97, 2177, 23058, 152979, 738835, 2839571, 9191876, 26037717, 66301333, 154762069, 336050870, 686502375, 1331121351, 2467171687, 4396168328, 7566347369, 12628007049, 20504452585, 32481640666, 50320004987, 76392352443, 113852150523, 166836980044, 240712403645
Offset: 1

Views

Author

Zak Seidov, Sep 24 2002

Keywords

Examples

			a(1) = 1^4 = 1; a(2) = 2^4 + 3^4 = 97; a(3) = 4^4 + 5^4 + 6^4 = 2177; a(4) = 7^4 + 8^4 + 9^4 + 10^4 = 23058.
		

Crossrefs

Cf. A000583 (4th powers).
Cf. A006003 (for natural numbers), A072474 (for squares), A075664 - A075671 (3rd to 10th powers), A069876 (n-th powers).

Programs

  • Mathematica
    i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=4; Table[Sum[i^s, {i, i1, i2}], {n, 20}]
    Table[Total[Range[(n(n+1))/2+1,((n+1)(n+2))/2]^4],{n,0,20}] (* or *) LinearRecurrence[{10,-45,120,-210,252,-210,120,-45,10,-1},{1,97,2177,23058,152979,738835,2839571,9191876,26037717,66301333},30] (* Harvey P. Dale, Dec 18 2015 *)

Formula

a(n) = Sum_{i=n*(n-1)/2+1..n*(n-1)/2+n} i^4.
a(n) = (15*n^9 + 90*n^7 + 123*n^5 + 20*n^3 - 8*n)/240. - Charles R Greathouse IV, Sep 17 2009
G.f.: x*(1+87*x+1252*x^2+5533*x^3+8934*x^4+5533*x^5+1252*x^6+87*x^7+x^8)/ (1-x)^10. - Colin Barker, May 25 2012

A075670 Sum of next n 9th powers.

Original entry on oeis.org

1, 20195, 12292965, 1561991824, 77226633575, 2014634387961, 33098483802475, 383318212734080, 3377498614484589, 23898971839102975, 141290020118952881, 719054471032657200, 3223613105991831475, 12964037775857022869, 47453810583528962775, 159982264435790734336
Offset: 1

Views

Author

Zak Seidov, Sep 24 2002

Keywords

Examples

			a(1) = 1^9 = 1; a(2) = 2^9 + 3^9 = 20195; a(3) = 4^9 + 5^9 + 6^9 = 12292965; a(4) = 7^9 + 8^9 + 9^9 + 10^9 = 1561991824.
		

Crossrefs

Cf. A001017 (9th powers).
Cf. A006003, A072474 (for squares), A075664 - A075671 (3rd to 10th powers), A069876 (n-th powers).

Programs

  • Magma
    [(5*n^19 + 105*n^17 + 666*n^15 + 1530*n^13 + 689*n^11 - 995*n^9 + 304*n^7 + 640*n^5 - 384*n^3)/2560 : n in [1..20]]; // Vincenzo Librandi, Oct 06 2011
  • Mathematica
    i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=9; Table[Sum[i^s, {i, i1, i2}], {n, 20}]
    Total[#^9]&/@(Range[First[#]+1,Last[#]]&/@Partition[Accumulate[Range[ 0,15]],2,1]) (* Harvey P. Dale, Oct 05 2011 *)
    With[{nn=20},Total/@TakeList[Range[(nn(nn+1))/2]^9,Range[nn]]] (* Harvey P. Dale, Aug 05 2025 *)

Formula

a(n) = Sum_{i=n(n-1)/2+1..n(n-1)/2+n} i^9.
a(n) = (5n^19 + 105n^17 + 666n^15 + 1530n^13 + 689n^11 - 995n^9 + 304n^7 + 640n^5 - 384n^3)/2560. - Charles R Greathouse IV, Sep 17 2009
G.f.: x*(x^18 +20175*x^17 +11889255*x^16 +1319968434*x^15 +48299442990*x^14 +752964012192*x^13 +5757432094050*x^12 +23468751060270*x^11 +53583908362248*x^10 +70362713036770*x^9 +53583908362248*x^8 +23468751060270*x^7 +5757432094050*x^6+752964012192*x^5 +48299442990*x^4 +1319968434*x^3 +11889255*x^2 +20175*x +1)/(x -1)^20. - Colin Barker, Sep 06 2012

A372751 a(n) = (3*n^5 + 4*n^3 - n)/6.

Original entry on oeis.org

1, 21, 139, 554, 1645, 4031, 8631, 16724, 30009, 50665, 81411, 125566, 187109, 270739, 381935, 527016, 713201, 948669, 1242619, 1605330, 2048221, 2583911, 3226279, 3990524, 4893225, 5952401, 7187571, 8619814, 10271829, 12167995, 14334431, 16799056, 19591649
Offset: 1

Views

Author

Kelvin Voskuijl, May 12 2024

Keywords

Comments

Sums of hexagonal numbers (A000384) in successive groups of length 1,2,3,etc, so 1, 6+15, 28+45+66, 91+120+153+190, etc.

Examples

			The hexagonal numbers and their groups summed begin
  1, 6, 15, 28, 45, 66, 91, 120, 153, 190
  \/ \---/  \--------/  \---------------/
  1,   21,     139,            554
		

Crossrefs

Cf. A000384 (hexagonal numbers), A002412 (their partial sums).
Cf. A260513 (for triangular numbers), A072474 (for squares), A372583 (for pentagonal numbers), A075664 (cubes).

Programs

Formula

From Stefano Spezia, May 12 2024: (Start)
G.f.: x*(1 + 15*x + 28*x^2 + 15*x^3 + x^4)/(1 - x)^6.
E.g.f.: exp(x)*x*(6 + 57*x + 79*x^2 + 30*x^3 + 3*x^4)/6. (End)

A075666 Sum of next n 5th powers.

Original entry on oeis.org

1, 275, 11925, 208624, 2078375, 14118201, 72758875, 304553600, 1084203549, 3390961375, 9540835601, 24582546000, 58801331875, 131987718149, 280410672375, 567799960576, 1102105900025, 2060382328875, 3724847929549, 6534040766000, 11154010982751, 18575718271825
Offset: 1

Views

Author

Zak Seidov, Sep 24 2002

Keywords

Examples

			a(1) = 1^5 = 1; a(2) = 2^5 + 3^5 = 275; a(3) = 4^5 + 5^5 + 6^5 = 11925; a(4) = 7^5 + 8^5 + 9^5 + 10^5 = 208624.
		

Crossrefs

Cf. A000584 (5th powers).
Cf. A072474 (for squares), A075664 - A075671 (3rd to 10th powers), A069876 (n-th powers).

Programs

  • Mathematica
    i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=5; Table[Sum[i^s, {i, i1, i2}], {n, 20}]
    nn=30;With[{p5=Range[((nn+1)(nn+2))/2]^5},Join[{1},Table[Total[Take[p5,{(n(n+1))/2+1,((n+1)(n+2))/2}]],{n,nn}]]] (* Harvey P. Dale, Mar 09 2014 *)
    Module[{nn=25,p5},p5=Range[(nn(nn+1))/2]^5;Total/@TakeList[p5,Range[nn]]] (* Harvey P. Dale, Oct 13 2023 *)

Formula

a(n) = Sum_{i=n(n-1)/2+1..n(n-1)/2+n} i^5.
a(n) = (3n^11 + 25n^9 + 53n^7 + 23n^5 - 8n^3)/96. - Charles R Greathouse IV, Sep 17 2009
G.f.: x*(x^10 +263*x^9 +8691*x^8 +83454*x^7 +301932*x^6 +458718*x^5 +301932*x^4 +83454*x^3 +8691*x^2 +263*x+1) / (x-1)^12. - Colin Barker, Jul 22 2012

A075667 Sum of next n 6th powers.

Original entry on oeis.org

1, 793, 66377, 1911234, 28504515, 271739011, 1874885963, 10136389172, 45311985069, 173957200405, 589679082421, 1802148522758, 5045944649967, 13108508706879, 31915866810295, 73427944186856, 160710828298553, 336507487921137, 677266380588289, 1315464522556810
Offset: 1

Views

Author

Zak Seidov, Sep 24 2002

Keywords

Examples

			a(1) = 1^6 = 1; a(2) = 2^6 + 3^6 = 793; a(3) = 4^6 + 5^6 + 6^6 = 66377; a(4) = 7^6 + 8^6 + 9^6 + 10^6 = 1911234.
		

Crossrefs

Cf. A001014 (6th powers).
Cf. A006003, A072474 (for squares), A075664 - A075671 (3rd to 10th powers), A069876 (n-th powers).

Programs

  • Mathematica
    i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=6; Table[Sum[i^s, {i, i1, i2}], {n, 20}]
    With[{nn=20},Total/@TakeList[Range[(nn(nn+1))/2]^6,Range[nn]]] (* or *) LinearRecurrence[{14,-91,364,-1001,2002,-3003,3432,-3003,2002,-1001,364,-91,14,-1},{1,793,66377,1911234,28504515,271739011,1874885963,10136389172,45311985069,173957200405,589679082421,1802148522758,5045944649967,13108508706879},20] (* Harvey P. Dale, Mar 29 2022 *)

Formula

a(n) = Sum_{i=n(n-1)/2+1..n(n-1)/2+n} i^6.
a(n) = (21n^13 + 231n^11 + 693n^9 + 549n^7 - 126n^5 - 56n^3 + 32n)/1344. - Charles R Greathouse IV, Sep 17 2009
G.f.: x*(x^12 +779*x^11 +55366*x^10 +1053755*x^9 +7499895*x^8 +23228658*x^7 +33620292*x^6 +23228658*x^5 +7499895*x^4 +1053755*x^3 +55366*x^2 +779*x +1)/(x-1)^14. - Colin Barker, Jul 22 2012

A075668 Sum of next n 7th powers.

Original entry on oeis.org

1, 2315, 374445, 17703664, 394340375, 5265954441, 48574262275, 338837482880, 1900477947429, 8950536157375, 36536761179281, 132397570996560, 433806511149115, 1303971065324669, 3637715990646375, 9507513902672896, 23461050872397545, 55013865421504275
Offset: 1

Views

Author

Zak Seidov, Sep 24 2002

Keywords

Examples

			a(1) = 1^7 = 1; a(2) = 2^7 + 3^7 = 2315; a(3) = 4^7 + 5^7 + 6^7 = 374445; a(4) = 7^7 + 8^7 + 9^7 + 10^7 = 17703664.
		

Crossrefs

Cf. A001015 (7th powers).
Cf. A006003 (for natural numbers), A072474 (for squares), A075664 - A075671 (for 3rd to 10th powers), A069876 (n-th powers).

Programs

  • Mathematica
    i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=7; Table[Sum[i^s, {i, i1, i2}], {n, 20}]

Formula

a(n) = Sum_{i=n*(n-1)/2+1..n*(n-1)/2+n} i^7.
a(n) = (3*n^15 + 42*n^13 + 168*n^11 + 206*n^9 - 11*n^7 - 56*n^5 + 32*n^3)/384. - Charles R Greathouse IV, Sep 17 2009
G.f.: x*(x^14 +2299*x^13 +337525*x^12 +11989784*x^11 +154720571*x^10 +875467853*x^9 +2397170367*x^8 +3336829200*x^7 +2397170367*x^6 +875467853*x^5 +154720571*x^4 +11989784*x^3 +337525*x^2 +2299*x +1)/(x-1)^16. - Colin Barker, Jul 22 2012

A075669 Sum of next n 8th powers.

Original entry on oeis.org

1, 6817, 2135777, 165588738, 5498750979, 102697107715, 1264908663011, 11373936899396, 79985007371877, 461856872635333, 2269365182729029, 9747136491367430, 37362375267437415, 129917413702762791, 415196000174767687, 1232554282743058568, 3428668198703973449
Offset: 1

Views

Author

Zak Seidov, Sep 24 2002

Keywords

Examples

			a(1) = 1^8 = 1; a(2) = 2^8 + 3^8 = 6817; a(3) = 4^8 + 5^8 + 6^8 = 2135777; a(4) = 7^8 + 8^8 + 9^8 + 10^8 = 165588738.
		

Crossrefs

Cf. A001016 (8th powers).
Cf. A006003 (for natural numbers), A072474 (for squares), A075664 - A075671 (for 3rd to 10th powers), A069876 (for n-th powers).

Programs

  • Mathematica
    i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=8; Table[Sum[i^s, {i, i1, i2}], {n, 20}]

Formula

a(n) = Sum_{i=n*(n-1)/2+1..n*(n-1)/2+n} i^8.
a(n) = (45*n^17 + 780*n^15 + 3990*n^13 + 6900*n^11 + 1205*n^9 - 3240*n^7 + 1584*n^5 + 640*n^3 - 384*n)/11520. - Charles R Greathouse IV, Sep 17 2009
G.f.: x*(x^16 +6799*x^15 +2013224*x^14 +128186937*x^13 +2839367964*x^12 +27332724427*x^11 +129026301848*x^10 +319786366637*x^9 +431174080326*x^8 +319786366637*x^7 +129026301848*x^6 +27332724427*x^5 +2839367964*x^4 +128186937*x^3 +2013224*x^2 +6799*x +1)/(x -1)^18. - Colin Barker, Sep 06 2012
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