A256180 -id:A256180 - cp's OEIS frontend

A274804 The exponential transform of sigma(n).

1, 1, 4, 14, 69, 367, 2284, 15430, 115146, 924555, 7991892, 73547322, 718621516, 7410375897, 80405501540, 914492881330, 10873902417225, 134808633318271, 1738734267608613, 23282225008741565, 323082222240744379, 4638440974576329923, 68794595993688306903

Offset: 0

Johannes W. Meijer, Jul 27 2016

nonn

The exponential transform [EXP] transforms an input sequence b(n) into the output sequence a(n). The EXP transform is the inverse of the logarithmic transform [LOG], see the Weisstein link and the Sloane and Plouffe reference. This relation goes by the name of Riddell's formula. For information about the logarithmic transform see A274805. The EXP transform is related to the multinomial transform, see A274760 and the second formula.
The definition of the EXP transform, see the second formula, shows that n >= 1. To preserve the identity LOG[EXP[b(n)]] = b(n) for n >= 0 for a sequence b(n) with offset 0 the shifted sequence b(n-1) with offset 1 has to be used as input for the exponential transform, otherwise information about b(0) will be lost in transformation.
In the a(n) formulas, see the examples, the multinomial coefficients A178867 appear.
We observe that a(0) = 1 and provides no information about any value of b(n), this notwithstanding it is customary to start the a(n) sequence with a(0) = 1.
The Maple programs can be used to generate the exponential transform of a sequence. The first program uses a formula found by Alois P. Heinz, see A007446 and the first formula. The second program uses the definition of the exponential transform, see the Weisstein link and the second formula. The third program uses information about the inverse of the exponential transform, see A274805.
Some EXP transform pairs are, n >= 1: A000435(n) and A065440(n-1); 1/A000027(n) and A177208(n-1)/A177209(n-1); A000670(n) and A075729(n-1); A000670(n-1) and A014304(n-1); A000045(n) and A256180(n-1); A000290(n) and A033462(n-1); A006125(n) and A197505(n-1); A053549(n) and A198046(n-1); A000311(n) and A006351(n); A030019(n) and A134954(n-1); A038048(n) and A053529(n-1); A193356(n) and A003727(n-1).

			Some a(n) formulas, see A178867:
a(0) = 1
a(1) = x(1)
a(2) = x(1)^2 + x(2)
a(3) = x(1)^3 + 3*x(1)*x(2) + x(3)
a(4) = x(1)^4 + 6*x(1)^2*x(2) + 4*x(1)*x(3) + 3*x(2)^2 + x(4)
a(5) = x(1)^5 + 10*x(1)^3*x(2) + 10*x(1)^2*x(3) + 15*x(1)*x(2)^2 + 5*x(1)*x(4) + 10*x(2)*x(3) + x(5)

Frank Harary and Edgar M. Palmer, Graphical Enumeration, 1973.
Robert James Riddell, Contributions to the theory of condensation, Dissertation, University of Michigan, Ann Arbor, 1951.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 1995, pp. 18-23.

Alois P. Heinz, Table of n, a(n) for n = 0..531
M. Bernstein and N. J. A. Sloane, Some Canonical Sequences of Integers, Linear Algebra and its Applications, Vol. 226-228 (1995), pp. 57-72. Erratum 320 (2000), 210. [Link to arXiv version]
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
N. J. A. Sloane, Transforms.
Eric W. Weisstein MathWorld, Exponential Transform.

Cf. A274805, A274760, A178867, A000203, A007446.
Cf. A177208, A177209, A006351, A197505, A144180, A256180, A033462, A198046, A134954, A145460, A188489, A005432, A029725, A124213, A002801.
Cf. A036040, another version.

nmax:=21: with(numtheory): b := proc(n): sigma(n) end: a:= proc(n) option remember; if n=0 then 1 else add(binomial(n-1, j-1) * b(j) *a(n-j), j=1..n) fi: end: seq(a(n), n=0..nmax); # End first EXP program.
nmax:= 21: with(numtheory): b := proc(n): sigma(n) end: t1 := exp(add(b(n)*x^n/n!, n=1..nmax+1)): t2 := series(t1, x, nmax+1): a := proc(n): n!*coeff(t2, x, n) end: seq(a(n), n=0..nmax); # End second EXP program.
nmax:=21: with(numtheory): b := proc(n): sigma(n) end: f := series(log(1+add(q(n)*x^n/n!, n=1..nmax+1)), x, nmax+1): d := proc(n): n!*coeff(f, x, n) end: a(0):=1: q(0):=1: a(1):=b(1): q(1):=b(1): for n from 2 to nmax+1 do q(n) := solve(d(n)-b(n), q(n)): a(n):=q(n): od: seq(a(n), n=0..nmax); # End third EXP program.

a[0] = 1; a[n_] := a[n] = Sum[Binomial[n-1, j-1]*DivisorSigma[1, j]*a[n-j], {j, 1, n}]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Feb 22 2017 *)
nmax = 20; CoefficientList[Series[Exp[Sum[DivisorSigma[1, k]*x^k/k!, {k, 1, nmax}]], {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Jun 08 2021 *)

a(n) = Sum_{j=1..n} (binomial(n-1,j-1) * b(j) * a(n-j)), n >= 1 and a(0) = 1, with b(n) = A000203(n) = sigma(n).

E.g.f.: exp(Sum_{n >= 1} b(n)*x^n/n!) with b(n) = sigma(n) = A000203(n).

A112005 Logarithmic transform of Fibonacci numbers A000045.

Original entry on oeis.org

0, 1, 0, 1, -2, 4, -17, 82, -384, 2189, -14850, 107404, -845537, 7400482, -70093256, 709888645, -7721333538, 89774204756, -1107347563761, 14456268008050, -199350032354000, 2893615098314941, -44089764970860290, 703841452185590236, -11747695951762870497

Offset: 0

Wolfdieter Lang, Sep 12 2005

Alois P. Heinz, Table of n, a(n) for n = 0..200
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to arXiv version]
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
N. J. A. Sloane, Transforms
Index entries for sequences related to logarithmic numbers

Cf. A007553, A112006, A256180.

a:= proc(n) option remember; (t-> `if`(n=0, 0, t(n) -add(j*t(n-j)*
      binomial(n, j)*a(j), j=1..n-1)/n))(i->(<<0|1>, <1|1>>^i)[1, 2])
    end:
seq(a(n), n=0..25);  # Alois P. Heinz, Mar 06 2018

FullSimplify[CoefficientList[Series[Log[1 + 2*E^(x/2)*Sinh[Sqrt[5]*x/2] / Sqrt[5]], {x, 0, 20}], x] * Range[0, 20]!] (* Vaclav Kotesovec, Sep 04 2014 *)

E.g.f. log(1 + A(x)) with the e.g.f. A(x):=exp(x/2)*sinh(sqrt(5)*x/2)/(sqrt(5)/2) of A000045.

a(n) ~ -(n-1)! / r^n, where r = -1.37807491378452630283968362340785266756... is the root of the equation 2*(5-3*sqrt(5))*r + (sqrt(5)-5) * (log(5/4) + 2*log(1-coth(sqrt(5)*r/2))) = 0. - Vaclav Kotesovec, Sep 04 2014

A346415 Triangle T(n,k), n>=0, 0<=k<=n, read by rows, where column k is (1/k!) times the k-fold exponential convolution of Fibonacci numbers with themselves.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 3, 1, 0, 3, 11, 6, 1, 0, 5, 35, 35, 10, 1, 0, 8, 115, 180, 85, 15, 1, 0, 13, 371, 910, 630, 175, 21, 1, 0, 21, 1203, 4494, 4445, 1750, 322, 28, 1, 0, 34, 3891, 22049, 30282, 16275, 4158, 546, 36, 1, 0, 55, 12595, 107580, 202565, 144375, 49035, 8820, 870, 45, 1

Offset: 0

Alois P. Heinz, Jul 15 2021

The sequence of column k>0 satisfies a linear recurrence with constant coefficients of order k+1.

			Triangle T(n,k) begins:
  1;
  0,  1;
  0,  1,     1;
  0,  2,     3,      1;
  0,  3,    11,      6,      1;
  0,  5,    35,     35,     10,      1;
  0,  8,   115,    180,     85,     15,     1;
  0, 13,   371,    910,    630,    175,    21,    1;
  0, 21,  1203,   4494,   4445,   1750,   322,   28,   1;
  0, 34,  3891,  22049,  30282,  16275,  4158,  546,  36,  1;
  0, 55, 12595, 107580, 202565, 144375, 49035, 8820, 870, 45, 1;
  ...

Alois P. Heinz, Rows n = 0..140, flattened

Columns k=0-4 give: A000007, A000045, A014335, A014337, A014341.
T(n+j,n) for j=0-2 give: A000012, A000217, A000914.
Row sums give A256180.

b:= proc(n) option remember; `if`(n=0, 1, add(expand(x*b(n-j)
      *binomial(n-1, j-1)*(<<0|1>, <1|1>>^j)[1, 2]), j=1..n))
    end:
T:= n-> (p-> seq(coeff(p, x, i), i=0..n))(b(n)):
seq(T(n), n=0..12);
# second Maple program:
b:= proc(n, k) option remember; `if`(k=0, 0^n, `if`(k=1,
       combinat[fibonacci](n), (q-> add(binomial(n, j)*
       b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
    end:
T:= (n, k)-> b(n, k)/k!:
seq(seq(T(n, k), k=0..n), n=0..12);

b[n_, k_] := b[n, k] = If[k == 0, 0^n, If[k == 1, Fibonacci[n], With[{q = Quotient[k, 2]}, Sum[Binomial[n, j] b[j, q] b[n-j, k-q], {j, 0, n}]]]];
T[n_, k_] := b[n, k]/k!;
Table[Table[T[n, k], {k, 0, n}], {n, 0, 12}] // Flatten (* Jean-François Alcover, Nov 06 2021, after 2nd Maple program *)

A006701 Exponentiation of g.f. for Fibonacci numbers.

Original entry on oeis.org

0, 1, 1, 5, 13, 60, 246, 1266, 6679, 39568, 247940, 1677435, 12020295, 91463410, 733490265, 6189608760, 54746987035, 506444804075, 4887127598817, 49096724251235, 512474550910080, 5548429401985372, 62208756548406172, 721256031012180537, 8635815672831322186

Offset: 0

N. J. A. Sloane

nonn

Vaclav Kotesovec, Table of n, a(n) for n = 0..500

Cf. A000045, A007552, A256180.

a[-1] = 1; a[n_] := a[n] = Sum[Binomial[n, k]*Fibonacci[k]*a[n - k - 1], {k, 0, n}]; Table[a[n], {n, 0, 30}] (* Vaclav Kotesovec, Jun 08 2021 *)

a(n) = if (n==-1, 1, sum(k=0, n, binomial(n,k)*fibonacci(k)*a(n-k-1))); \\ Michel Marcus, Jun 11 2017

a(-1) = 1, a(n) = Sum_{k=0..n} binomial(n, k) * A000045(k) * a(n-k-1). - Sean A. Irvine, Jun 11 2017

A007552 Exponentiation of Fibonacci numbers.

Original entry on oeis.org

1, 3, 10, 42, 204, 1127, 6924, 46704, 342167, 2700295, 22799218, 204799885, 1947993126, 19540680497, 206001380039, 2275381566909, 26261810071925, 315969045744894, 3954454344433658, 51382626410402336, 691956435942841207

Offset: 1

N. J. A. Sloane

nonn

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Alois P. Heinz, Table of n, a(n) for n = 1..500
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, arXiv:math/0205301 [math.CO], 2002. [pLink to arXiv version]
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]

Cf. A006701, A256180.

f:= proc(n) option remember; `if`(n<2, 1, f(n-1) +f(n-2)) end: a:= proc(n) option remember; f(n) +add(binomial(n-1, k-1) *f(k) *a(n-k), k=1..n-1) end: seq(a(n), n=1..30); # Alois P. Heinz, Oct 07 2008

f[n_] := f[n] = If[n<2, 1, f[n-1]+f[n-2]]; a[n_] := a[n] = f[n]+Sum [Binomial[n-1, k-1]*f[k]*a[n-k], {k, 1, n-1}]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Mar 03 2014, after Alois P. Heinz *)

Vec(serlaplace(exp( serconvol(Ser(1/(1-x-x^2)),exp(x))-1)))
/* ==> [1, 1, 3, 10, 42, 204, 1127, 6924, 46704,...] (note offset 0) */
/* Joerg Arndt, Jun 16 2010 */

E.g.f.: exp(exp(x/2)*(sqrt(5)*cosh(x*sqrt(5)/2)+sinh(x*sqrt(5)/2))/sqrt(5)-1)-1. - Vladimir Kruchinin, Feb 27 2015

A279271 Exponential transform of the Pell numbers.

Original entry on oeis.org

1, 1, 3, 12, 57, 320, 2065, 14954, 119585, 1044184, 9867633, 100185294, 1086173121, 12510549116, 152422123321, 1956974934290, 26391647743937, 372769201632784, 5500416368181921, 84594395013757398, 1353277808896178145, 22476374660911200068, 386925983827921358665, 6893254434792968631674

Offset: 0

Ilya Gutkovskiy, Dec 12 2016

nonn

			E.g.f.: A(x) = 1 + x/1! + 3*x^2/2! + 12*x^3/3! + 57*x^4/4! + 320*x^5/5! + 2065*x^6/6! + ...

M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to arXiv version]
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
N. J. A. Sloane, Transforms
Eric W. Weisstein MathWorld, Exponential Transform
Eric Weisstein's World of Mathematics, Pell Number

Cf. A000129, A256180.

Range[0, 23]! CoefficientList[Series[Exp[Exp[x] Sinh[Sqrt[2] x]/Sqrt[2]], {x, 0, 23}], x]

x='x + O('x^30); round( Vec(serlaplace(exp(exp(x)*sinh(sqrt(2)*x) /sqrt(2)))) ) \\ G. C. Greubel, Dec 13 2016

E.g.f.: exp(exp(x)*sinh(sqrt(2)*x)/sqrt(2)).

A294222 Exponential transform of the Lucas numbers (A000204).

Original entry on oeis.org

1, 1, 4, 14, 69, 372, 2320, 15913, 119938, 978456, 8586177, 80456488, 800905726, 8429875989, 93453556378, 1087491751050, 13244265431889, 168370713583760, 2229127899764052, 30671277674880073, 437770190804865414, 6470590710038358164, 98891186448861721537, 1560548838446810788940, 25394750159240696915562

Offset: 0

Ilya Gutkovskiy, Oct 25 2017

nonn

			E.g.f.: A(x) = 1 + x/1! + 4*x^2/2! + 14*x^3/3! + 69*x^4/4! + 372*x^5/5! + 2320*x^6/6! + ...

M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to arXiv version]
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
N. J. A. Sloane, Transforms
Eric Weisstein's World of Mathematics, Exponential Transform
Eric Weisstein's World of Mathematics, Lucas Number

Cf. A000204, A256180, A279271.

Range[0, 24]! CoefficientList[Series[Exp[2 Exp[x/2] Cosh[Sqrt[5] x/2] - 2], {x, 0, 24}], x]
a[n_] := a[n] = Sum[a[n - k] Binomial[n - 1, k - 1] LucasL[k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 24}]

E.g.f.: exp(2*exp(x/2)*cosh(sqrt(5)*x/2) - 2).

cp's OEIS Frontend

A274804 The exponential transform of sigma(n).

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A112005 Logarithmic transform of Fibonacci numbers A000045.

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A346415 Triangle T(n,k), n>=0, 0<=k<=n, read by rows, where column k is (1/k!) times the k-fold exponential convolution of Fibonacci numbers with themselves.

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A006701 Exponentiation of g.f. for Fibonacci numbers.

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A007552 Exponentiation of Fibonacci numbers.

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A279271 Exponential transform of the Pell numbers.

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A294222 Exponential transform of the Lucas numbers (A000204).

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