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.

Previous Showing 11-14 of 14 results.

A144072 Euler transform of powers of 8.

Original entry on oeis.org

1, 8, 100, 1144, 12906, 141848, 1532276, 16290920, 170938483, 1773107760, 18208004664, 185316171472, 1871103319988, 18756665504080, 186798940872312, 1849265718114736, 18207140415436701, 178355043327697976, 1738966407826985884, 16881111732250394440
Offset: 0

Views

Author

Alois P. Heinz, Sep 09 2008

Keywords

Crossrefs

8th column of A144074.
Cf. A001018 (powers of 8).

Programs

  • Maple
    with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; `if`(n=0, 1, add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n) end end: a:=n-> etr(j->8^j)(n): seq(a(n), n=0..40);
  • Mathematica
    nmax = 20; CoefficientList[Series[Product[1/(1-x^j)^(8^j), {j, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Mar 14 2015 *)

Formula

G.f.: Product_{j>0} 1/(1-x^j)^(8^j).
a(n) ~ 8^n * exp(2*sqrt(n) - 1/2 + c) / (2 * sqrt(Pi) * n^(3/4)), where c = Sum_{m>=2} 1/(m*(8^(m-1)-1)) = 0.0772633520042039151361539536110877247158170... . - Vaclav Kotesovec, Mar 14 2015
G.f.: exp(8*Sum_{k>=1} x^k/(k*(1 - 8*x^k))). - Ilya Gutkovskiy, Nov 10 2018

A144073 Euler transform of powers of 9.

Original entry on oeis.org

1, 9, 126, 1623, 20583, 254493, 3091803, 36974025, 436377771, 5091463423, 58811218362, 673298882775, 7647050353038, 86229872235432, 966019964324004, 10757807941399023, 119146632352548516, 1312935665205028374, 14400230629085596621, 157253909597473608945
Offset: 0

Views

Author

Alois P. Heinz, Sep 09 2008

Keywords

Crossrefs

9th column of A144074.
Cf. A001019 (powers of 9).

Programs

  • Maple
    with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; `if`(n=0, 1, add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n) end end: a:=n-> etr(j->9^j)(n): seq(a(n), n=0..40);
  • Mathematica
    nmax = 20; CoefficientList[Series[Product[1/(1-x^j)^(9^j), {j, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Mar 14 2015 *)

Formula

G.f.: Product_{j>0} 1/(1-x^j)^(9^j).
a(n) ~ 9^n * exp(2*sqrt(n) - 1/2 + c) / (2 * sqrt(Pi) * n^(3/4)), where c = Sum_{m>=2} 1/(m*(9^(m-1)-1)) = 0.0670436814415340801450018457068097893307906... . - Vaclav Kotesovec, Mar 14 2015
G.f.: exp(9*Sum_{k>=1} x^k/(k*(1 - 9*x^k))). - Ilya Gutkovskiy, Nov 10 2018

A292837 Euler transform of powers of 10.

Original entry on oeis.org

1, 10, 155, 2220, 31265, 429502, 5796455, 77009640, 1009734835, 13088591470, 167965714273, 2136403822060, 26958029557805, 337733366170870, 4203655872002815, 52010628718162744, 639999271669543500, 7835602953248681200, 95484165081421513000
Offset: 0

Views

Author

Alois P. Heinz, Sep 24 2017

Keywords

Crossrefs

Column k=10 of A144074.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, add(add(d*
          10^d, d=numtheory[divisors](j))*a(n-j), j=1..n)/n)
        end:
    seq(a(n), n=0..30);

Formula

G.f.: Product_{j>0} 1/(1-x^j)^(10^j).
a(n) ~ 10^n * exp(2*sqrt(n) - 1/2 + c) / (2 * sqrt(Pi) * n^(3/4)), where c = Sum_{m>=2} 1/(m*(10^(m-1)-1)) = 0.0591946344347498235857176537123415539... - Vaclav Kotesovec, Sep 28 2017
G.f.: exp(10*Sum_{k>=1} x^k/(k*(1 - 10*x^k))). - Ilya Gutkovskiy, Nov 10 2018

A256105 a(n) = [x^n] 2^(2*n) / Product_{k>=1} (1-x^k)^(2^(-k)).

Original entry on oeis.org

1, 2, 10, 36, 166, 556, 2724, 9000, 41542, 153164, 657644, 2325816, 11020508, 38006264, 164662664, 634362320, 2695771462, 9775537676, 43527018396, 156855914904, 687387270260, 2605392165928, 10799896586616, 40214700074800, 178809945153820, 657023566793400
Offset: 0

Views

Author

Vaclav Kotesovec, Mar 14 2015

Keywords

Comments

Limit n->infinity a(n)^(1/n) = 4.

Crossrefs

Programs

  • Mathematica
    Table[2^(2*n) * SeriesCoefficient[Product[1/(1-x^k)^(2^(-k)),{k,1,n}],{x,0,n}], {n,0,30}]
    Table[4^n * (CoefficientList[Series[Exp[Sum[x^k/(2*k*(1-x^k/2)),{k,1,n}]],{x,0,n}],x])[[n+1]],{n,0,30}] (* faster *)
Previous Showing 11-14 of 14 results.