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 1-8 of 8 results.

A303641 Decimal expansion of a constant related to the asymptotics of A323575.

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Jan 19 2019

Keywords

Examples

			2.4736552566321294876378936942724280363620971232545793827877...
		

Crossrefs

Cf. A323575.

Formula

Equals limit_{n->infinity} A323575(n) / (n^(n*(n+1)/2) * 2^(n^2/2) / exp(n^2/2)).

A323588 a(n) = Product_{k=1..n} (k^n + (n-k)^n).

Original entry on oeis.org

1, 1, 8, 2187, 55083008, 248292236328125, 287440081598682287308800, 136294854579772162759923622710449623, 32534104705262209051040075603284216686012438413312, 5686543339012978225006873713961872387810223003912610672810622880089
Offset: 0

Views

Author

Vaclav Kotesovec, Jan 18 2019

Keywords

Crossrefs

Programs

  • Magma
    [1] cat [(&*[k^n +(n-k)^n: k in [1..n]]): n in [1..10]]; // G. C. Greubel, Feb 08 2019
    
  • Mathematica
    Table[Product[k^n+(n-k)^n, {k, 1, n}], {n, 0, 10}]
  • PARI
    vector(10, n, n--; prod(k=1,n, k^n+(n-k)^n)) \\ G. C. Greubel, Feb 08 2019
    
  • Sage
    [product(k^n +(n-k)^n for k in (1..n)) for n in (0..10)] # G. C. Greubel, Feb 08 2019

Formula

a(n) ~ c * 2^(n^2) * n^(n^2) / exp(n^2), where
c = 1.7567468186007109703792640049745420817202851050652253469714... if n is even,
c = 1.8080216158688347442204158454365469233524049331246880759722... if n is odd.

A323589 a(n) = Product_{k=1..n-1} (k^k + (n-k)^(n-k)).

Original entry on oeis.org

1, 1, 2, 25, 6272, 63473089, 35671256150400, 1706937496190389809801, 7511133178157708431911079116800, 4755809816953036991699151550498501702425129, 394143276257895110158515904775794405720952934400000000000
Offset: 0

Views

Author

Vaclav Kotesovec, Jan 18 2019

Keywords

Crossrefs

Programs

  • Magma
    [1,1] cat [(&*[k^k + (n-k)^(n-k): k in [1..n-1]]): n in [2..12]]; // G. C. Greubel, Feb 08 2019
    
  • Mathematica
    Table[Product[k^k+(n-k)^(n-k), {k, 1, n-1}], {n, 0, 12}]
  • PARI
    vector(12, n, n--; prod(k=1,n-1, k^k+(n-k)^(n-k))) \\ G. C. Greubel, Feb 08 2019
    
  • Sage
    [product(k^k + (n-k)^(n-k) for k in (1..n-1)) for n in (0..12)] # G. C. Greubel, Feb 08 2019

Formula

a(n) ~ n^(3*n^2/4 - n) * 2^(n^2/4 + 7/6) / exp(3*n^2/8) if n is even.
a(n) ~ n^(3*n^2/4 - n + 1/4) * 2^(n^2/4 - 1/12) / exp(3*n^2/8 - 1/4) if n is odd.

A323702 a(n) = Product_{k=0..n} (k! + (n-k)!).

Original entry on oeis.org

2, 4, 18, 441, 122500, 585640000, 61740367761072, 176956326932345427600, 16411667387809544192807523072, 59483286633748316026134239331720597504, 9536532654533775992805729638288082189179486453760, 81298938207133741609860679855100783339855352530145447380582400
Offset: 0

Views

Author

Vaclav Kotesovec, Jan 24 2019

Keywords

Crossrefs

Programs

  • Magma
    [(&*[Factorial(j)+Factorial(n-j): j in [0..n]]): n in [0..20]]; // G. C. Greubel, Aug 30 2023
    
  • Mathematica
    Table[Product[k! + (n-k)!, {k, 0, n}], {n, 0, 12}]
  • PARI
    a(n) = prod(k=0, n, k! + (n-k)!); \\ Michel Marcus, Jan 24 2019
    
  • SageMath
    [product(factorial(j)+factorial(n-j) for j in range(n+1)) for n in range(21)] # G. C. Greubel, Aug 30 2023

Formula

a(n) ~ 2^(n^2/4 + n + 11/6) * n^(3*n*(n+2)/4 + 1/2) * Pi^((n+1)/2) / exp(3*n*(3*n+4)/8) if n is even.
a(n) ~ 2^(n^2/4 + n + 7/12) * n^(3*(n+1)^2 / 4) * Pi^((n+1)/2) / exp(3*n*(3*n+4)/8) if n is odd.

A323751 a(n) = Product_{k=0..n} (k^n + (n-k)^n).

Original entry on oeis.org

2, 1, 32, 59049, 14101250048, 775913238525390625, 13410804447068120796679372800, 112244673425189306235795780017831813874289, 545831702006800417886454373052629612732034857946832699392
Offset: 0

Views

Author

Seiichi Manyama, Jan 26 2019

Keywords

Crossrefs

Programs

  • Magma
    [(&*[k^n +(n-k)^n: k in [0..n]]): n in [0..10]]; // G. C. Greubel, Feb 08 2019
    
  • Mathematica
    Table[Product[k^n+(n-k)^n, {k,0,n}], {n,0,10}] (* G. C. Greubel, Feb 08 2019 *)
  • PARI
    {a(n) = prod(k=0, n, k^n+(n-k)^n)}
    
  • Sage
    [product(k^n +(n-k)^n for k in (0..n)) for n in (0..10)] # G. C. Greubel, Feb 08 2019

Formula

a(n) = n^n * A323588(n). - Vaclav Kotesovec, Feb 08 2019

A366305 a(n) = Product_{k=1..n} (k^n + (k-1)^n).

Original entry on oeis.org

1, 5, 315, 555713, 47705305725, 305469864195354625, 207095306530955763265880535, 20017329298655447986400838721630926977, 357361761140807273279996172600335233468472149678425, 1481824279740988988264353294673429995981921700740921435758587890625
Offset: 1

Views

Author

Vaclav Kotesovec, Oct 06 2023

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Product[k^n + (k-1)^n, {k, 1, n}], {n, 1, 10}]

Formula

a(n) = (n!)^n * Product_{k=1..n} (1 + (1 - 1/k)^n).
a(n) ~ n!^n * d^n, where d = exp(Integral_{x=0..1} log(1 + exp(-1/x)) dx) = 1.14183186235785012136459060138978468902610644657603999829892450823456733...
a(n) ~ (2*Pi)^(n/2) * d^n * n^(n*(2*n+1)/2) / exp(n^2 - 1/12).

A366271 Decimal expansion of limit_{n->oo} Product_{k=1..n} ((k/n)^(k/n) + (1 - k/n)^(k/n))^(1/n).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Oct 06 2023

Keywords

Comments

Limit_{n->oo} Product_{k=1..n} (k/n)^(k/n^2) = exp(-1/4).

Examples

			1.38489201265986890417861106075712813583048148929763977709475...
		

Crossrefs

Cf. A323575.

Programs

  • Mathematica
    RealDigits[Exp@NIntegrate[Log[1+(1/r-1)^r], {r, 0, 1}, WorkingPrecision->120] * Exp[-1/4], 10, 105][[1]]

Formula

Equals exp(-1/4 + Integral_{x=0..1} log(1 + (1/x - 1)^x) dx).
Conjecture: Limit_{n->oo} (1/A366271^n) * Product_{k=1..n} ((k/n)^(k/n) + (1 - k/n)^(k/n)) = 1/sqrt(2).

A366306 a(n) = Product_{k=1..n} (k^n - (k-1)^n).

Original entry on oeis.org

1, 3, 133, 170625, 10733002621, 50465283999665535, 25145494699347449245677097, 1787473773567267792523164108726890625, 23480751910878672340765325385856840967957995534681, 71672834655019406921956925590632596034005848922160549420728589375
Offset: 1

Views

Author

Vaclav Kotesovec, Oct 06 2023

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Product[k^n - (k-1)^n, {k, 1, n}], {n, 1, 10}]

Formula

a(n) = (n!)^n * Product_{k=1..n} (1 - (1 - 1/k)^n).
a(n) ~ n!^n * d^n, where d = exp(Integral_{x=0..1} log(1 - exp(-1/x)) dx) = 0.84207793096051704199642805288991601369639823969574423397520945175552718...
a(n) ~ (2*Pi)^(n/2) * d^n * n^(n*(2*n+1)/2) / exp(n^2 - 1/12).
Showing 1-8 of 8 results.