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 1-10 of 13 results. Next

A008778 a(n) = (n+1)*(n^2 +8*n +6)/6. Number of n-dimensional partitions of 4. Number of terms in 4th derivative of a function composed with itself n times.

Original entry on oeis.org

1, 5, 13, 26, 45, 71, 105, 148, 201, 265, 341, 430, 533, 651, 785, 936, 1105, 1293, 1501, 1730, 1981, 2255, 2553, 2876, 3225, 3601, 4005, 4438, 4901, 5395, 5921, 6480, 7073, 7701, 8365, 9066, 9805, 10583, 11401, 12260, 13161, 14105, 15093, 16126, 17205, 18331
Offset: 0

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Keywords

Comments

Let m(i,1)=i; m(1,j)=j; m(i,j)=m(i-1,j)-m(i-1,j-1); then a(n)=m(n+3,3) - Benoit Cloitre, May 08 2002
a(n) = number of (n+6)-bit binary sequences with exactly 6 1's none of which is isolated. - David Callan, Jul 15 2004
If a 2-set Y and 2-set Z, having one element in common, are subsets of an n-set X then a(n-4) is the number of 4-subsets of X intersecting both Y and Z. - Milan Janjic, Oct 03 2007
Sum of first n triangular numbers plus previous triangular number. - Vladimir Joseph Stephan Orlovsky, Oct 13 2009
a(n) = Sum of first (n+1) triangular numbers plus n-th triangular number (see penultimate formula by Henry Bottomley). - Vladimir Joseph Stephan Orlovsky, Oct 13 2009
For n > 0, a(n-1) is the number of compositions of n+6 into n parts avoiding the part 2. - Milan Janjic, Jan 07 2016
The binomial transform of [1,4,4,1,0,0,0,...], the 4th row in A116672. - R. J. Mathar, Jul 18 2017

Examples

			G.f. = 1 + 5*x + 13*x^2 + 26*x^3 + 45*x^4 + 71*x^5 + 105*x^6 + 148*x^7 + 201*x^8 + ...
		

References

  • G. E. Andrews, The Theory of Partitions, Addison-Wesley, 1976, p. 190 eq. (11.4.7).

Crossrefs

Column 1 of triangle A094415.
Row n=4 of A022818.
Cf. A002411, A008779, A005712 (partial sums), A034856 (first diffs).

Programs

  • GAP
    List([0..50], n-> (n+1)*(n^2 +8*n +6)/6); # G. C. Greubel, Sep 11 2019
  • Magma
    [(n+1)*(n^2+8*n+6)/6: n in [0..50]]; // Vincenzo Librandi, May 21 2011
    
  • Maple
    seq(1+4*k+4*binomial(k, 2)+binomial(k, 3), k=0..45);
  • Mathematica
    Table[(n+1)*(n^2+8*n+6)/6, {n,0,50}] (* Vladimir Joseph Stephan Orlovsky, Oct 13 2009, modified by G. C. Greubel, Sep 11 2019 *)
    LinearRecurrence[{4,-6,4,-1}, {1,5,13,26}, 51] (* G. C. Greubel, Sep 11 2019 *)
  • PARI
    Vec((1+x-x^2)/(1-x)^4 + O(x^50)) \\ Altug Alkan, Jan 07 2016
    
  • Sage
    [(n+1)*(n^2 +8*n +6)/6 for n in (0..50)] # G. C. Greubel, Sep 11 2019
    

Formula

a(n) = dot_product(n, n-1, ...2, 1)*(2, 3, ..., n, 1) for n = 2, 3, 4, ... [i.e., a(2) = (2, 1)*(2, 1), a(3) = (3, 2, 1)*(2, 3, 1)]. - Clark Kimberling
a(n) = a(n-1) + A034856(n+1) = A000297(n-1) + 1 = A000217(n) + A000292(n+1) = A000290(n-1) + A000292(n). - Henry Bottomley, Oct 25 2001
a(n) = Sum_{0<=k, l<=n; k+l|n} k*l. - Ralf Stephan, May 06 2005
G.f.: (1+x-x^2)/(1-x)^4. - Colin Barker, Jan 06 2012
a(n) = A000330(n+1) - A000292(n-1). - Bruce J. Nicholson, Jul 05 2018
E.g.f.: (6 +24*x +12*x^2 +x^3)*exp(x)/6. - G. C. Greubel, Sep 11 2019

A022811 Number of terms in n-th derivative of a function composed with itself 3 times.

Original entry on oeis.org

1, 1, 3, 6, 13, 23, 44, 74, 129, 210, 345, 542, 858, 1310, 2004, 2996, 4467, 6540, 9552, 13744, 19711, 27943, 39452, 55172, 76865, 106200, 146173, 199806, 272075, 368247, 496642, 666201, 890602, 1184957, 1571417, 2075058, 2731677, 3582119, 4683595, 6102256
Offset: 0

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Author

Winston C. Yang (yang(AT)math.wisc.edu)

Keywords

Comments

This also counts a restricted set of plane partitions of n. Each element of the set which contains the A000041(n) partitions of n can be converted into plane partitions by insertion of line feeds at some or all places of the "pluses." Since the length of rows in plane partitions must be nonincreasing, there are only A000041(L(P)) ways to comply with this rule, where L(P) is the number of terms in that particular partition. Example for n=4: consider all five partitions 4 = 3+1 = 2+2 = 2+1+1 = 1+1+1+1 of four. The associated a(4)=13 plane partitions are 4, 31, 3|1, 22, 2|2, 211, 21|1, 2|1|1, 1111, 111|1, 11|11, 11|1|1 and 1|1|1|1, where the bar represents start of the next row, where a(4) = A000041(L(4)) + A000041(L(3+1)) + A000041(L(2+2)) + A000041(L(2+1+1))+ A000041(L(1+1+1+1)) = A000041(1) + A000041(2) + A000041(2) + A000041(3) + A000041(4). By construction from sorted partitions, all the plane partitions are strictly decreasing along each row and each column. - R. J. Mathar, Aug 12 2008
Also the number of pairs of integer partitions, the first with sum n and the second with sum equal to the length of the first. - Gus Wiseman, Jul 19 2018

Examples

			From _Gus Wiseman_, Jul 19 2018: (Start)
Using the chain rule, we compute the second derivative of f(f(f(x))) to be the following sum of a(2) = 3 terms.
  d^2/dx^2 f(f(f(x))) =
  f'(f(x)) f'(f(f(x))) f''(x) +
  f'(x)^2 f'(f(f(x))) f''(f(x)) +
  f'(x)^2 f'(f(x))^2 f''(f(f(x))).
(End)
		

References

  • W. C. Yang, Derivatives of self-compositions of functions, preprint, 1997.

Crossrefs

Column k=3 of A022818.
First column of A039805.
A row or column of A081718.

Programs

  • Maple
    A022811 := proc(n) local a,P,p,lp ; a := 0 ; P := combinat[partition](n) ; for p in P do lp := nops(p) ; a := a+combinat[numbpart](lp) ; od: RETURN(a) ; end: for n from 1 do print(n,A022811(n)) ; od: # R. J. Mathar, Aug 12 2008
  • Mathematica
    a[n_] := Total[PartitionsP[Length[#]]& /@ IntegerPartitions[n]];
    Table[an = a[n]; Print["a(", n, ") = ", an]; an, {n, 0, 80}] (* Jean-François Alcover, Apr 28 2017 *)
    Table[Length[1+D[f[f[f[x]]],{x,n}]]-1,{n,10}] (* Gus Wiseman, Jul 19 2018 *)

Formula

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = Sum_{i=0..m} p(m,i)*a(n-1,i).
G.f.: Sum_{k>=0} p(k) * x^k / Product_{j=1..k} (1 - x^j), where p(k) = number of partitions of k. - Ilya Gutkovskiy, Jan 28 2020

Extensions

Typo corrected by Neven Juric, Mar 25 2013

A022818 Square array read by antidiagonals: A(n,k) = number of terms in the n-th derivative of a function composed with itself k times (n, k >= 1).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 6, 5, 1, 1, 5, 10, 13, 7, 1, 1, 6, 15, 26, 23, 11, 1, 1, 7, 21, 45, 55, 44, 15, 1, 1, 8, 28, 71, 110, 121, 74, 22, 1, 1, 9, 36, 105, 196, 271, 237, 129, 30, 1, 1, 10, 45, 148, 322, 532, 599, 468, 210, 42, 1, 1, 11, 55, 201, 498, 952, 1301, 1309, 867, 345, 56, 1
Offset: 1

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Keywords

Examples

			Square array A(n,k) (with rows n >= 1 and columns k >= 1) begins:
  1,  1,   1,   1,    1,    1,    1,     1, ...
  1,  2,   3,   4,    5,    6,    7,     8, ...
  1,  3,   6,  10,   15,   21,   28,    36, ...
  1,  5,  13,  26,   45,   71,  105,   148, ...
  1,  7,  23,  55,  110,  196,  322,   498, ...
  1, 11,  44, 121,  271,  532,  952,  1590, ...
  1, 15,  74, 237,  599, 1301, 2541,  4586, ...
  1, 22, 129, 468, 1309, 3101, 6539, 12644, ...
  ...
		

References

  • Winston C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Crossrefs

Main diagonal gives: A192435.

Programs

  • Maple
    A:= proc(n, k) option remember;
          `if`(k=1, 1, add(b(n, n, i)*A(i, k-1), i=0..n))
        end:
    b:= proc(n, i, k) option remember; `if`(nAlois P. Heinz, Aug 18 2012
    # second Maple program:
    b:= proc(n, i, l, k) option remember; `if`(k=0,
          `if`(n<2, 1, 0), `if`(n=0 or i=1, b(l+n$2, 0, k-1),
             b(n, i-1, l, k) +b(n-i, min(n-i, i), l+1, k)))
        end:
    A:= (n, k)->  b(n$2, 0, k):
    seq(seq(A(n, 1+d-n), n=1..d), d=1..12);  # Alois P. Heinz, Jul 19 2018
  • Mathematica
    a[n_, k_] := a[n, k] = If[k == 1, 1, Sum[b[n, n, i]*a[i, k-1], {i, 0, n}]]; b[n_, i_, k_] := b[n, i, k] = If[n < k, 0, If[n == 0, 1, If[i < 1, 0, Sum[b[n-i*j, i-1, k-j], {j, 0, Min[n/i, k]}]]]]; Table[Table[a[n, 1+d-n], {n, 1, d}], {d, 1, 12}] // Flatten (* Jean-François Alcover, Jan 14 2014, translated from Alois P. Heinz's Maple code *)
  • PARI
    P(n, k) = #partitions(n-k, k); /* A008284 */
    tabl(nn) = {M = matrix(nn, nn, n, k, 0); for(n=1, nn, M[n, 1] = 1; ); for(n=1, nn, for(k=2, nn, M[n, k] = sum(s=1, n, P(n, s)*M[s, k-1]))); for (n=1, nn, for (k=1, nn, print1(M[n, k], ", "); ); print(); ); } \\ Petros Hadjicostas, May 30 2020

Formula

From Petros Hadjicostas, May 30 2020: (Start)
A(n,k) = Sum_{s=1..n} A008284(n,s)*A(s,k-1) for n >= 1 and k >= 2 with A(n,1) = 1 for n >= 1.
A(n,k) = Sum_{s=1..n} binomial(k,s-1)*A081719(n-1,s-1) for n, k >= 1. (End)

Extensions

Edited by Alois P. Heinz, Aug 18 2012

A024207 Number of terms in n-th derivative of a function composed with itself 7 times.

Original entry on oeis.org

1, 1, 7, 28, 105, 322, 952, 2541, 6539, 15833, 37148, 83594, 183289, 389520, 809820, 1643375, 3272797, 6390745, 12279337, 23208483, 43252360, 79483096, 144265338, 258673983, 458747540, 804877837, 1398356706, 2406328974, 4104352128, 6940717598, 11643270856
Offset: 0

Views

Author

Winston C. Yang (yang(AT)math.wisc.edu)

Keywords

References

  • W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Crossrefs

Cf. A008778, A022811-A022817, A024208-A024210. First column of A050301.
Column k=7 of A022818.

Programs

  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n < k, 0, If[n == 0, 1, If[i < 1, 0, Sum[b[n - i*j, i - 1, k - j], {j, 0, Min[n/i, k]}]]]];
    a[n_, k_] := a[n, k] = If[k == 1, 1, Sum[b[n, n, i]*a[i, k-1], {i, 0, n}]];
    a[n_] := a[n, 7];
    Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

Formula

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).

Extensions

More terms from Alois P. Heinz, Aug 18 2012

A022817 Number of terms in 7th derivative of a function composed with itself n times.

Original entry on oeis.org

1, 15, 74, 237, 599, 1301, 2541, 4586, 7785, 12583, 19536, 29327, 42783, 60893, 84827, 115956, 155873, 206415, 269686, 348081, 444311, 561429, 702857, 872414, 1074345, 1313351, 1594620, 1923859, 2307327, 2751869, 3264951, 3854696, 4529921, 5300175, 6175778
Offset: 1

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Author

Keywords

References

  • W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Crossrefs

Programs

  • Maple
    a:= n-> n*(36+(-356+(645+(355+(39+n)*n)*n)*n)*n)/720:
    seq(a(n), n=1..40);  # Alois P. Heinz, Aug 18 2012
  • Mathematica
    Table[(n/720*(n^5+39*n^4+355*n^3+645*n^2-356*n+36)),{n,1,100}] (* Vincenzo Librandi, Aug 18 2012 *)

Formula

a(n) = n/720 * (n^5 + 39*n^4 + 355*n^3 + 645*n^2 - 356*n + 36).
G.f.: (x^5-4*x^4+x^3+10*x^2-8*x-1)*x/(x-1)^7. - Alois P. Heinz, Aug 18 2012

Extensions

More terms from Christian G. Bower, Aug 15 1999.

A022812 Number of terms in n-th derivative of a function composed with itself 4 times.

Original entry on oeis.org

1, 1, 4, 10, 26, 55, 121, 237, 468, 867, 1597, 2821, 4952, 8421, 14206, 23439, 38324, 61570, 98112, 154111, 240197, 370015, 565802, 856664, 1288366, 1921016, 2846572, 4186730, 6122369, 8893904, 12851713, 18460961, 26388354, 37519159, 53101687, 74792210
Offset: 0

Views

Author

Winston C. Yang (yang(AT)math.wisc.edu)

Keywords

References

  • W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Crossrefs

Cf. A008778, A022811-A022818, A024207-A024210. First column of A039806.

Programs

  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n < k, 0, If[n == 0, 1, If[i < 1, 0, Sum[b[n - i*j, i - 1, k - j], {j, 0, Min[n/i, k]}]]]];
    a[n_, k_] := a[n, k] = If[k == 1, 1, Sum[b[n, n, i]*a[i, k-1], {i, 0, n}]];
    a[n_] := a[n, 4]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

Formula

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).

A022813 Number of terms in n-th derivative of a function composed with itself 5 times.

Original entry on oeis.org

1, 1, 5, 15, 45, 110, 271, 599, 1309, 2690, 5436, 10545, 20148, 37341, 68223, 121878, 214846, 371993, 636570, 1073325, 1790721, 2950922, 4816603, 7778937, 12455988, 19761148, 31108121, 48572686, 75307513, 115909727, 177255526, 269294119, 406708721, 610593948
Offset: 0

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Author

Winston C. Yang (yang(AT)math.wisc.edu)

Keywords

References

  • W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Crossrefs

Cf. A008778, A022811-A022818, A024207-A024210. First column of A039807.

Programs

  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[nJean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

Formula

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).

A022814 Number of terms in n-th derivative of a function composed with itself 6 times.

Original entry on oeis.org

1, 1, 6, 21, 71, 196, 532, 1301, 3101, 6956, 15217, 31951, 65670, 130914, 256150, 489690, 920905, 1699693, 3092751, 5540571, 9802091, 17114237, 29550346, 50444952, 85264328, 142682505, 236649524, 389033014, 634408230, 1026350152, 1648328017, 2628254619
Offset: 0

Views

Author

Winston C. Yang (yang(AT)math.wisc.edu)

Keywords

References

  • W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Crossrefs

Cf. A008778, A022811-A022818, A024207-A024210. First column of A050300.

Programs

  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[nJean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

Formula

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).

A022815 Number of terms in 5th derivative of a function composed with itself n times.

Original entry on oeis.org

1, 7, 23, 55, 110, 196, 322, 498, 735, 1045, 1441, 1937, 2548, 3290, 4180, 5236, 6477, 7923, 9595, 11515, 13706, 16192, 18998, 22150, 25675, 29601, 33957, 38773, 44080, 49910, 56296, 63272, 70873, 79135, 88095, 97791, 108262, 119548, 131690
Offset: 1

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Author

Keywords

Examples

			a(7) = 7*28 + (7*0+6*1+5*3+4*6+3*10+2*15+1*21) = 322. [_Bruno Berselli_, Jun 22 2013]
		

References

  • W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Crossrefs

Programs

Formula

a(n) = n*(n+1)*(n^2+13*n-2)/24. - John W. Layman, Apr 27 2000
G.f.: x*(1-2*x^2+2*x)/(1-x)^5. [Maksym Voznyy (voznyy(AT)mail.ru), Aug 11 2009]
a(n) = n*A000217(n) + sum((n-i)*A000217(i), i=0..n-1). [Bruno Berselli, Jun 23 2013]

Extensions

G.f. proposed by Maksym Voznyy checked and corrected by R. J. Mathar, Sep 16 2009.
More terms from Christian G. Bower, Aug 15 1999.

A024208 Number of terms in n-th derivative of a function composed with itself 8 times.

Original entry on oeis.org

1, 1, 8, 36, 148, 498, 1590, 4586, 12644, 32775, 81901, 196085, 455772, 1025779, 2252674, 4823546, 10116553, 20783490, 41949270, 83211931, 162552093, 312850854, 594086542, 1113610526, 2062796698, 3777567977, 6844786250, 12276620372, 21809737429, 38391720375
Offset: 0

Views

Author

Winston C. Yang (yang(AT)math.wisc.edu)

Keywords

References

  • W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Crossrefs

Cf. A008778, A022811-A022817, A024207-A024210. First column of A050302.
Column k=8 of A022818.

Programs

  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[nJean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

Formula

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).
Showing 1-10 of 13 results. Next