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.

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A320782 Inverse Euler transform of the unsigned Moebius function A008966.

Original entry on oeis.org

1, 1, 0, 0, -1, 1, 0, 0, -1, 1, 0, 0, -2, 3, 0, -1, -3, 6, -3, 0, -6, 12, -6, 0, -9, 23, -17, 0, -15, 47, -40, 8, -24, 91, -101, 34, -46, 181, -230, 109, -92, 354, -534, 323, -208, 690, -1177, 883, -520, 1365, -2603, 2297, -1377, 2760, -5641, 5789, -3721, 5741
Offset: 0

Views

Author

Gus Wiseman, Oct 22 2018

Keywords

Comments

The Euler transform of a sequence q is the sequence of coefficients of x^n, n > 0, in the expansion of Product_{n > 0} 1/(1 - x^n)^q(n). The constant term 1 is sometimes taken to be the zeroth part of the Euler transform.

Crossrefs

Number theoretical functions: A000005, A000010, A000203, A001055, A001221, A001222, A008683, A010054.
Inverse Euler transforms: A059966, A320767, A320776, A320777, A320778, A320779, A320780, A320781.

Programs

  • Mathematica
    EulerInvTransform[{}]={};EulerInvTransform[seq_]:=Module[{final={}},For[i=1,i<=Length[seq],i++,AppendTo[final,i*seq[[i]]-Sum[final[[d]]*seq[[i-d]],{d,i-1}]]];
    Table[Sum[MoebiusMu[i/d]*final[[d]],{d,Divisors[i]}]/i,{i,Length[seq]}]];
    EulerInvTransform[Table[Abs[MoebiusMu[n]],{n,30}]]

A306327 Expansion of Product_{k>=1} 1/(1 - mu(k)*x^k), where mu() is the Möbius function (A008683).

Original entry on oeis.org

1, 1, 0, -1, 0, 0, 1, 0, 0, -1, 2, 0, 1, -2, 2, 0, 4, -4, 1, -4, 6, -2, 8, -8, 6, -7, 13, -10, 13, -16, 17, -17, 22, -25, 29, -26, 40, -37, 40, -50, 58, -56, 69, -75, 82, -90, 108, -110, 128, -133, 158, -168, 185, -207, 229, -238, 281, -298, 328, -357, 405, -417, 477, -518, 564, -608
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 07 2019

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 65; CoefficientList[Series[Product[1/(1 - MoebiusMu[k] x^k), {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 65; CoefficientList[Series[Exp[Sum[Sum[MoebiusMu[j]^k x^(j k)/k, {j, 1, nmax}], {k, 1, nmax}]], {x, 0, nmax}], x]
    a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d MoebiusMu[d]^(k/d), {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 65}]

Formula

G.f.: exp(Sum_{k>=1} Sum_{j>=1} mu(j)^k*x^(j*k)/k).

A300673 Expansion of e.g.f. exp(Sum_{k>=1} mu(k)*x^k/k!), where mu() is the Moebius function (A008683).

Original entry on oeis.org

1, 1, 0, -3, -6, 5, 61, 126, -308, -2772, -5669, 25630, 224730, 486551, -3068155, -29264219, -72173176, 513535711, 5625869262, 16687752839, -113740116822, -1496118902963, -5508392724427, 31534346503605, 523333047780288, 2414704077547660, -10254467367668159
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 11 2018

Keywords

Comments

Exponential transform of A008683.

Examples

			E.g.f.: A(x) = 1 + x/1! - 3*x^3/3! - 6*x^4/4! + 5*x^5/5! + 61*x^6/6! + 126*x^7/7! - 308*x^8/8! - 2772*x^9/9! - 5669*x^10/10! + ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 26; CoefficientList[Series[Exp[Sum[MoebiusMu[k] x^k/k!, {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
    a[n_] := a[n] = Sum[MoebiusMu[k] Binomial[n - 1, k - 1] a[n - k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 26}]
  • PARI
    a(n) = if(n==0, 1, sum(k=1, n, moebius(k)*binomial(n-1, k-1)*a(n-k))); \\ Seiichi Manyama, Feb 27 2022

Formula

E.g.f.: exp(Sum_{k>=1} A008683(k)*x^k/k!).
a(0) = 1; a(n) = Sum_{k=1..n} mu(k) * binomial(n-1,k-1) * a(n-k). - Seiichi Manyama, Feb 27 2022

A307648 G.f. A(x) satisfies: 1/(1 - x) = A(x)*A(x^2)^2*A(x^3)^3*A(x^4)^4* ... *A(x^k)^k* ...

Original entry on oeis.org

1, 1, -1, -4, -3, -2, 7, 7, 4, -6, 14, -11, -4, -47, 9, 6, 161, -93, -33, -269, 232, -83, 660, -733, 500, -779, 1527, -2291, 1876, -3892, 5598, -3056, 7791, -14088, 11289, -17113, 28083, -26211, 34645, -60715, 73180, -80951, 111926, -155269, 178561, -233709, 359679, -403884, 454659, -697310, 862133
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 19 2019

Keywords

Comments

Euler transform of A055615.

Examples

			G.f.: A(x) = 1 + x - x^2 - 4*x^3 - 3*x^4 - 2*x^5 + 7*x^6 + 7*x^7 + 4*x^8 - 6*x^9 + 14*x^10 - 11*x^11 - 4*x^12 - 47*x^13 + ...
		

Crossrefs

Programs

  • Mathematica
    terms = 50; CoefficientList[Series[Product[1/(1 - x^k)^(MoebiusMu[k] k), {k, 1, terms}], {x, 0, terms}], x]
    terms = 50; CoefficientList[Series[Exp[Sum[Sum[MoebiusMu[d] d^2, {d, Divisors[k]}] x^k/k, {k, 1, terms}]], {x, 0, terms}], x]
    terms = 50; A[] = 1; Do[A[x] = 1/((1 - x) Product[A[x^k]^k, {k, 2, terms}]) + O[x]^(terms + 1) // Normal, terms + 1]; CoefficientList[A[x], x]

Formula

G.f.: Product_{k>=1} 1/(1 - x^k)^(mu(k)*k).
G.f.: exp(Sum_{k>=1} A046970(k)*x^k/k).

A268649 G.f. A(x) satisfies: 1/(1-x) = Product_{n>=1} A( x^n/(1+x)^n ).

Original entry on oeis.org

1, 1, 1, 2, 4, 9, 17, 36, 71, 143, 284, 573, 1140, 2287, 4568, 9138, 18272, 36559, 73098, 146216, 292413, 584836, 1169657, 2339353, 4678655, 9357356, 18714673, 37429377, 74858706, 149717506, 299434883, 598869895, 1197739689, 2395479446, 4790958784, 9581917760, 19163835261, 38327670814, 76655341388, 153310682944, 306621365618, 613242731721, 1226485462828, 2452970926285, 4905941852039, 9811883704440, 19623767408346, 39247534817726, 78495069634129
Offset: 0

Views

Author

Paul D. Hanna, Mar 26 2016

Keywords

Comments

Compare g.f. to the identity: x = Sum_{n>=1} x^n/(1+x)^n.

Examples

			G.f.: A(x) = 1 + x + x^2 + 2*x^3 + 4*x^4 + 9*x^5 + 17*x^6 + 36*x^7 + 71*x^8 + 143*x^9 + 284*x^10 + 573*x^11 + 1140*x^12 +...
where
1/(1-x) = A(x/(1+x)) * A(x^2/(1+x)^2) * A(x^3/(1+x)^3) * A(x^4/(1+x)^4) * A(x^5/(1+x)^5) *...
RELATED SERIES.
A(x/(1+x)) = 1 + x + x^3 + 2*x^5 - 4*x^6 + 14*x^7 - 35*x^8 + 86*x^9 - 191*x^10 +...
A(x^2/(1+x)^2) = 1 + x^2 - 2*x^3 + 4*x^4 - 8*x^5 + 17*x^6 - 38*x^7 + 88*x^8 +...
A(x^3/(1+x)^3) = 1 + x^3 - 3*x^4 + 6*x^5 - 9*x^6 + 9*x^7 - 26*x^9 + 72*x^10 +...
A(x^4/(1+x)^4) = 1 + x^4 - 4*x^5 + 10*x^6 - 20*x^7 + 36*x^8 - 64*x^9 + 120*x^10 +...
A(x^5/(1+x)^5) = 1 + x^5 - 5*x^6 + 15*x^7 - 35*x^8 + 70*x^9 - 125*x^10 +...
		

Crossrefs

Cf. A117209.

Programs

  • PARI
    {a(n) = my(A=[1,1],X=x+x*O(x^n)); for(i=1,n, A=concat(A,0); A[#A] = 1 - Vec( prod(k=1,#A, subst(Ser(A),x,x^k/(1+X)^k)) )[#A] );A[n+1]}
    for(n=0,40,print1(a(n),", "))

Formula

G.f. satisfies: (1-x)/(1-2*x) = Product_{n>=1} A(x^n).
a(n) ~ c * 2^n, where c = 0.2788705076091492504414859194394933690344541628... . - Vaclav Kotesovec, Apr 02 2016

A307658 G.f. A(x) satisfies: (1 + x)/(1 - x) = A(x)*A(x^2)*A(x^3)*A(x^4)* ... *A(x^k)* ...

Original entry on oeis.org

1, 2, 0, -4, -4, 0, 4, 4, 0, -4, 0, 4, 0, -8, -4, 8, 16, 0, -20, -20, 8, 24, 20, -12, -24, -8, 24, 4, -16, -24, 16, 28, 24, -40, -32, 0, 72, 24, -28, -104, 0, 48, 88, -44, -32, -64, 92, 20, 24, -124, 64, 0, 96, -168, -12, -72, 272, -24, 72, -300, 104, -88, 316, -272, 128, -272, 376, -300
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 20 2019

Keywords

Comments

Convolution of A117209 and A117210.

Examples

			G.f.: A(x) = 1 + 2*x - 4*x^3 - 4*x^4 + 4*x^6 + 4*x^7 - 4*x^9 + 4*x^11 - 8*x^13 - 4*x^14 + 8*x^15 + ...
		

Crossrefs

Programs

  • Mathematica
    terms = 67; CoefficientList[Series[Product[((1 + x^k)/(1 - x^k))^MoebiusMu[k], {k, 1, terms}], {x, 0, terms}], x]
    terms = 67; A[] = 1; Do[A[x] = (1 + x)/((1 - x) Product[A[x^k], {k, 2, terms}]) + O[x]^(terms + 1) // Normal, terms + 1]; CoefficientList[A[x], x]

Formula

G.f.: Product_{k>=1} ((1 + x^k)/(1 - x^k))^mu(k).

A320784 Negated inverse Euler transform of {-1 if n is a triangular number else 0, n > 0} = -A010054.

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 2, 3, 3, 5, 8, 11, 14, 23, 31, 47, 68, 101, 144, 217, 315, 471, 693, 1035, 1528, 2287, 3397, 5085, 7587, 11377, 17017, 25565, 38349, 57681, 86724, 130645, 196778, 296853, 447864, 676479, 1022082, 1545685, 2338299, 3540111, 5361606, 8125551
Offset: 0

Views

Author

Gus Wiseman, Oct 22 2018

Keywords

Comments

The Euler transform of a sequence q is the sequence of coefficients of x^n, n > 0, in the expansion of Product_{n > 0} 1/(1 - x^n)^q(n). The constant term 1 is sometimes taken to be the zeroth part of the Euler transform.

Crossrefs

Programs

  • Mathematica
    EulerInvTransform[{}]={};EulerInvTransform[seq_]:=Module[{final={}},For[i=1,i<=Length[seq],i++,AppendTo[final,i*seq[[i]]-Sum[final[[d]]*seq[[i-d]],{d,i-1}]]];
    Table[Sum[MoebiusMu[i/d]*final[[d]],{d,Divisors[i]}]/i,{i,Length[seq]}]];
    -EulerInvTransform[-Table[SquaresR[1,8*n+1]/2,{n,30}]]

A351402 G.f. A(x) satisfies: 1 / (1 - x) = Product_{i>=1, j>=1} A(x^(i*j)).

Original entry on oeis.org

1, 1, -1, -3, -1, 1, 4, 2, -2, -5, 4, 2, -2, -10, 3, 10, 21, -15, -26, -23, 34, 28, 25, -54, -18, 2, 67, -48, -22, -55, 116, 44, 37, -227, -10, 32, 295, -85, -76, -336, 254, 74, 250, -451, 59, -127, 672, -294, -69, -761, 740, 77, 657, -1208, 59, -450, 1700, -487, 241, -1892, 1202
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 10 2022

Keywords

Comments

Euler transform of A007427.

Crossrefs

Programs

  • Mathematica
    nmax = 60; A007427[n_] := Sum[MoebiusMu[d] MoebiusMu[n/d], {d, Divisors[n]}]; CoefficientList[Series[Product[1/(1 - x^k)^A007427[k], {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f. A(x) satisfies: 1 / (1 - x) = Product_{k>=1} A(x^k)^A000005(k).
G.f.: Product_{k>=1} 1 / (1 - x^k)^A007427(k).
G.f.: exp( Sum_{k>=1} A101035(k) * x^k / k ).
a(0) = 1; a(n) = (1/n) * Sum_{k=1..n} A101035(k) * a(n-k).

A374364 Expansion of e.g.f. exp( x - Sum_{k>=1} x^(2^k)/2^k ).

Original entry on oeis.org

1, 1, 0, -2, -8, -24, 16, 400, -3072, -38528, -18944, 1287936, 17843200, 149045248, -188786688, -12007184384, -1265929355264, -20275964313600, 3871935889408, 2355175169523712, 45658709327609856, 565591105847689216, -1448855443865600000
Offset: 0

Views

Author

Seiichi Manyama, Jul 06 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x-sum(k=1, ceil(log(N+1)/log(2)), x^2^k/2^k))))

Formula

E.g.f.: Product_{k>=1} (1 + x^(2*k-1))^(mu(2*k-1)/(2*k-1)), where mu() is the Moebius function.

A320783 Inverse Euler transform of (-1)^(n - 1).

Original entry on oeis.org

1, 1, -2, 2, -3, 6, -11, 18, -30, 56, -105, 186, -335, 630, -1179, 2182, -4080, 7710, -14588, 27594, -52377, 99858, -190743, 364722, -698870, 1342176, -2581425, 4971008, -9586395, 18512790, -35792449, 69273666, -134215680, 260300986, -505294125, 981706806
Offset: 0

Views

Author

Gus Wiseman, Oct 22 2018

Keywords

Comments

After a(1) and a(2), same as A038063.
The Euler transform of a sequence q is the sequence of coefficients of x^n, n > 0, in the expansion of Product_{n > 0} 1/(1 - x^n)^q(n). The constant term 1 is sometimes taken to be the zeroth part of the Euler transform.

Crossrefs

Programs

  • Mathematica
    EulerInvTransform[{}]={};EulerInvTransform[seq_]:=Module[{final={}},For[i=1,i<=Length[seq],i++,AppendTo[final,i*seq[[i]]-Sum[final[[d]]*seq[[i-d]],{d,i-1}]]];
    Table[Sum[MoebiusMu[i/d]*final[[d]],{d,Divisors[i]}]/i,{i,Length[seq]}]];
    EulerInvTransform[Array[(-1)^(#-1)&,30]]
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