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 1-5 of 5 results.

A248619 a(n) = (n*(n+1))^4.

Original entry on oeis.org

0, 16, 1296, 20736, 160000, 810000, 3111696, 9834496, 26873856, 65610000, 146410000, 303595776, 592240896, 1097199376, 1944810000, 3317760000, 5473632256, 8767700496, 13680577296, 20851360000, 31116960000, 45558341136, 65554433296, 92844527616, 129600000000
Offset: 0

Views

Author

Eugene Chong, Oct 09 2014

Keywords

Crossrefs

Cf. A016744, A059977; A002378: n*(n+1); A035287: n^2 *(n-1)^2; A060459: n^3*(n+1)^3.
Cf. A327773.

Programs

  • Magma
    [(n*(n+1))^4: n in [0..30]]; // Vincenzo Librandi, Oct 16 2014
  • Maple
    [ seq(n^4*(n+1)^4, n = 0..100) ];
  • Mathematica
    Table[(n (n + 1))^4, {n, 0, 70}] (* or *) CoefficientList[Series[16 x (1 + 72 x + 603 x^2 + 1168 x^3 + 603 x^4 + 72 x^5 + x^6)/(1 - x)^9, {x, 0, 30}], x] (* Vincenzo Librandi, Oct 16 2014 *)
    LinearRecurrence[{9,-36,84,-126,126,-84,36,-9,1},{0,16,1296,20736,160000,810000,3111696,9834496,26873856},30] (* Harvey P. Dale, Sep 09 2016 *)

Formula

a(n) = A002378(n)^4 = A016744(A000217(n)).
a(n) = 16*A059977(n) for n>0.
G.f.: 16*x*(1 + 72*x + 603*x^2 + 1168*x^3 + 603*x^4 + 72*x^5 + x^6)/(1 - x)^9. - Vincenzo Librandi, Oct 16 2014
Sum_{n>=1} 1/a(n) = A327773 = -35 + 10*Pi^2/3 + Pi^4/45. - Vaclav Kotesovec, Sep 25 2019

Extensions

Terms a(76) and beyond corrected by Andrew Howroyd, Feb 20 2018

A348670 Decimal expansion of 10 - Pi^2.

Original entry on oeis.org

1, 3, 0, 3, 9, 5, 5, 9, 8, 9, 1, 0, 6, 4, 1, 3, 8, 1, 1, 6, 5, 5, 0, 9, 0, 0, 0, 1, 2, 3, 8, 4, 8, 8, 6, 4, 6, 8, 6, 3, 0, 0, 5, 9, 2, 7, 5, 9, 2, 0, 9, 3, 7, 3, 5, 8, 6, 6, 5, 0, 6, 2, 3, 7, 7, 9, 9, 5, 5, 1, 7, 7, 5, 8, 0, 7, 9, 4, 7, 5, 6, 9, 9, 8, 2, 2, 6, 5, 9, 6, 2, 8, 1, 4, 4, 7, 7, 6, 8, 1, 7, 5, 9, 7, 4
Offset: 0

Views

Author

Amiram Eldar, Oct 29 2021

Keywords

Comments

Let ABC be a unit-area triangle, and let P be a point uniformly picked at random inside it. Let D, E and F be the intersection points of the lines AP, BP and CP with the sides BC, CA and AB, respectively. Then, the expected value of the area of the triangle DEF is this constant.

Examples

			0.13039559891064138116550900012384886468630059275920...
		

References

  • Calvin C. Clawson, Mathematical Mysteries: The Beauty and Magic of Numbers, Springer, 2013, p. 220.
  • A. M. Mathai, An introduction to geometrical probability: distributional aspects with applications, Amsterdam: Gordon and Breach, 1999, p. 275, ex. 2.5.3.

Crossrefs

Programs

  • Mathematica
    RealDigits[10 - Pi^2, 10, 100][[1]]
  • PARI
    10 - Pi^2 \\ Michel Marcus, Oct 29 2021

Formula

Equals Sum_{k>=1} 1/(k*(k+1))^3 = Sum_{k>=1} 1/A060459(k).
Equals 6 * Sum_{k>=2} 1/(k*(k+1)^2*(k+2)) = Sum_{k>=3} 1/A008911(k).
Equals 2 * Integral_{x=0..1, y=0..1} x*(1-x)*y*(1-y)/(1-x*y)^2 dx dy.
Equals 4 * Sum_{m,n>=1} (m-n)^2/(m*n*(m+1)^2*(n+1)^2*(m+2)*(n+2)) (Sitaru, 2023). - Amiram Eldar, Aug 18 2023

A248720 a(n) = (n*(n+1))^5.

Original entry on oeis.org

0, 32, 7776, 248832, 3200000, 24300000, 130691232, 550731776, 1934917632, 5904900000, 16105100000, 40074642432, 92389579776, 199690286432, 408410100000, 796262400000, 1488827973632, 2682916351776, 4678757435232, 7923516800000, 13069123200000
Offset: 0

Views

Author

Eugene Chong, Oct 16 2014

Keywords

Comments

This is the sequence (2^5)*A059860(n)= (2*binomial(n+1,2))^5, n >= 0. - Wolfdieter Lang, Nov 03 2014

Crossrefs

Cf. A059860, A002378 (n*(n+1)), A035287(n+1) ((n*(n+1))^2), A060459 ((n*(n+1))^3), A248619 ((n*(n+1))^4).

Programs

  • Magma
    [(n*(n+1))^5: n in [0..30]];
  • Maple
    [ seq(n^5*(n+1)^5, n = 0..100) ];
  • Mathematica
    Table[(n (n + 1))^5, {n, 0, 70}] (* or *) CoefficientList[Series[32 x (x^8 + 232 x^7 + 5158 x^6 + 27664 x^5 + 47290 x^4 + 27664 x^3 + 5158 x^2 + 232 x + 1)/(1 - x)^11, {x, 0, 30}], x]
    LinearRecurrence[{11,-55,165,-330,462,-462,330,-165,55,-11,1},{0,32,7776,248832,3200000,24300000,130691232,550731776,1934917632,5904900000,16105100000},20] (* Harvey P. Dale, Apr 23 2017 *)

Formula

a(n) = A002378(n)^5.
a(n) = 32*A059860(n) for n>0.
G.f.: 32*x*(x^8 + 232*x^7 + 5158*x^6 + 27664*x^5 + 47290*x^4 + 27664*x^3 + 5158*x^2 + 232*x + 1) / (1 - x)^11 (from A059860).
Sum_{n>=1} 1/a(n) = 126 - 35*Pi^2/3 - Pi^4/9. - Vaclav Kotesovec, Sep 25 2019
a(n) = 11*a(n-1) - 55*a(n-2) + 165*a(n-3) - 330*a(n-4) + 462*a(n-5) - 462*a(n-6) + 330*a(n-7) - 165*a(n-8) + 55*a(n-9) - 11*a(n-10) + a(n-11). - Wesley Ivan Hurt, Jan 20 2024

Extensions

Terms a(32) and beyond corrected by Andrew Howroyd, Feb 20 2018

A249076 a(n) = (n*(n+1))^6.

Original entry on oeis.org

0, 64, 46656, 2985984, 64000000, 729000000, 5489031744, 30840979456, 139314069504, 531441000000, 1771561000000, 5289852801024, 14412774445056, 36343632130624, 85766121000000, 191102976000000, 404961208827904, 820972403643456, 1600135042849344, 3010936384000000, 5489031744000000
Offset: 0

Views

Author

Jiwoo Lee, Oct 20 2014

Keywords

Crossrefs

Cf. A059978; A002378: n*(n+1); A035282: n^2 *(n+1)^2; A060459: n^3 *(n+1)^3; A248619: n^4 *(n+1)^4;

Programs

  • Magma
    [(n*(n+1))^6: n in [0..30]];
    
  • Maple
    [ seq(n^6*(n+1)^6, n = 0..100) ];
  • Mathematica
    Table[(n (n + 1))^6, {n, 0, 70}] (* or *)
    CoefficientList[Series[64*x*(x^10 + 716 x^9 + 37257 x^8 + 450048 x^7 + 1822014 x^6 + 2864328 x^5 + 1822014 x^4 + 450048 x^3 + 37257 x^2 + 716 x + 1)/(1 - x)^13, {x, 0, 30}], x]
  • PARI
    a(n)=(n*(n+1))^6 \\ Charles R Greathouse IV, Oct 21 2014

Formula

a(n) = A002378(n)^6.
a(n) = 64*A059978(n) for n>0.
G.f.: 64*x*(x^10 + 716*x^9 + 37257*x^8 + 450048*x^7 + 1822014*x^6 + 2864328*x^5 + 1822014*x^4 + 450048*x^3 + 37257*x^2 + 716*x + 1)/(1 - x)^13. [corrected by Georg Fischer, May 10 2019]
Sum_{n>=1} 1/a(n) = -462 + 42*Pi^2 + 7*Pi^4/15 + 2*Pi^6/945. - Vaclav Kotesovec, Sep 25 2019

Extensions

Incorrect term corrected by Colin Barker, Oct 21 2014
Terms a(21) and beyond corrected by Andrew Howroyd, Feb 22 2018

A377567 Decimal expansion of 3*zeta(3)/2 + 12*log(2) - 10.

Original entry on oeis.org

1, 2, 0, 8, 5, 1, 5, 2, 1, 4, 5, 8, 7, 3, 5, 1, 4, 1, 1, 0, 6, 3, 9, 2, 6, 9, 9, 7, 6, 5, 2, 9, 3, 8, 0, 3, 0, 5, 3, 4, 8, 1, 0, 5, 0, 8, 3, 3, 8, 1, 1, 3, 7, 2, 1, 3, 6, 5, 6, 7, 4, 4, 6, 9, 3, 3, 4, 8, 0, 7, 7, 2, 3, 1, 5, 8, 0, 6, 2, 2, 2, 5, 5, 0, 0, 4, 3, 7, 3, 4, 3, 7, 1, 0, 2, 7, 1, 3, 7, 7
Offset: 0

Views

Author

Stefano Spezia, Nov 03 2024

Keywords

Examples

			0.12085152145873514110639269976529380305348105083381
		

References

  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 1.6.3, p. 44.

Crossrefs

Programs

  • Mathematica
    RealDigits[3Zeta[3]/2+12Log[2]-10,10,100][[1]]

Formula

Equals Sum_{k>=1} (-1)^(k+1)/(k^3*(k + 1)^3) (see Finch and Shamos).
Showing 1-5 of 5 results.