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 11 results. Next

A007563 Number of rooted connected graphs where every block is a complete graph.

Original entry on oeis.org

0, 1, 1, 3, 8, 25, 77, 258, 871, 3049, 10834, 39207, 143609, 532193, 1990163, 7503471, 28486071, 108809503, 417862340, 1612440612, 6248778642, 24309992576, 94905791606, 371691137827, 1459935388202, 5749666477454
Offset: 0

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Author

Keywords

References

  • F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 71, (3.4.13).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Column k=2 of A144042.
Cf. A245566.

Programs

  • Maple
    with(numtheory): etr:= proc(p) local b; b:= proc(n) option remember; if n=0 then 1 else (add(d*p(d), d=divisors(n)) +add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n-1))/n fi end end: b:= etr(a): c:= etr(b): a:= n-> if n=0 then 0 else c(n-1) fi: seq(a(n), n=0..25); # Alois P. Heinz, Sep 06 2008
  • Mathematica
    etr[p_] := etr[p] = Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[ Sum[ d*p[d], {d, Divisors[j]}]*b[n-j], {j, 1, n}]/n]; b]; a[0] = 0; a[n_] := etr[etr[a]][n-1]; Table[a[n], {n, 0, 25}] (* Jean-François Alcover, May 28 2013, after Alois P. Heinz *)
  • PARI
    EulerT(v)={Vec(exp(x*Ser(dirmul(v,vector(#v,n,1/n))))-1, -#v)}
    seq(n)={my(v=[1]); for(i=2, n, v=concat([1], EulerT(EulerT(v)))); concat([0], v)} \\ Andrew Howroyd, May 20 2018

Formula

Shifts left when Euler transform is applied twice.
a(n) ~ c * d^n / n^(3/2), where d = 4.189610958393826965527036454524044275... (see A245566), c = 0.1977574301782950818433893126632477845870281049591883888... . - Vaclav Kotesovec, Jul 26 2014

Extensions

New description from Christian G. Bower, Oct 15 1998

A316101 Sequence a_k of column k shifts left when Weigh transform is applied k times with a_k(n) = n for n<2; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 2, 1, 0, 1, 1, 1, 3, 3, 1, 0, 1, 1, 1, 4, 6, 6, 1, 0, 1, 1, 1, 5, 10, 16, 12, 1, 0, 1, 1, 1, 6, 15, 32, 43, 25, 1, 0, 1, 1, 1, 7, 21, 55, 105, 120, 52, 1, 0, 1, 1, 1, 8, 28, 86, 210, 356, 339, 113, 1, 0, 1, 1, 1, 9, 36, 126, 371, 826, 1227, 985, 247, 1
Offset: 0

Views

Author

Alois P. Heinz, Jun 24 2018

Keywords

Examples

			Square array A(n,k) begins:
  0,  0,   0,   0,   0,    0,    0,    0,    0, ...
  1,  1,   1,   1,   1,    1,    1,    1,    1, ...
  1,  1,   1,   1,   1,    1,    1,    1,    1, ...
  1,  1,   1,   1,   1,    1,    1,    1,    1, ...
  1,  2,   3,   4,   5,    6,    7,    8,    9, ...
  1,  3,   6,  10,  15,   21,   28,   36,   45, ...
  1,  6,  16,  32,  55,   86,  126,  176,  237, ...
  1, 12,  43, 105, 210,  371,  602,  918, 1335, ...
  1, 25, 120, 356, 826, 1647, 2961, 4936, 7767, ...
		

Crossrefs

Rows include (offsets may differ): A000004, A000012, A000027, A000217, A134465.
Main diagonal gives A316102.

Programs

  • Maple
    wtr:= proc(p) local b; b:= proc(n, i) option remember;
           `if`(n=0, 1, `if`(i<1, 0, add(binomial(p(i), j)*
             b(n-i*j, i-1), j=0..n/i))) end: j-> b(j$2)
          end:
    g:= proc(k) option remember; local b, t; b[0]:= j->
         `if`(j<2, j, b[k](j-1)); for t to k do
           b[t]:= wtr(b[t-1]) od: eval(b[0])
        end:
    A:= (n, k)-> g(k)(n):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    wtr[p_] := Module[{b}, b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[p[i], j]*b[n - i*j, i - 1], {j, 0, n/i}]]]; b[#, #]&];
    g[k_] := g[k] = Module[{b, t}, b[0][j_] := If[j < 2, j, b[k][j - 1]]; For[ t = 1, t <= k + 1, t++, b[t] = wtr[b[t - 1]]]; b[0]];
    A[n_, k_] := g[k][n];
    Table[A[n, d-n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, Jul 10 2018, after Alois P. Heinz *)

A305725 a(n) is the n-th term of the sequence that shifts left by one position when Euler transform is applied n times; a(0) = 0.

Original entry on oeis.org

0, 1, 1, 4, 19, 141, 1260, 14379, 192615, 2997844, 52869443, 1042233820, 22685350130, 540054008352, 13951013617182, 388499286052386, 11597298980187673, 369329248762633105, 12495176515326675179, 447453508295247538083, 16905177062269436114613
Offset: 0

Views

Author

Alois P. Heinz, Jun 21 2018

Keywords

Crossrefs

Main diagonal of A144042.

Formula

a(n) = A144042(n,n) for n>0, a(0) = 0.

A144035 Shifts left when Euler transform applied 3 times.

Original entry on oeis.org

0, 1, 1, 4, 13, 51, 197, 828, 3526, 15538, 69627, 317564, 1466868, 6853320, 32317354, 153636769, 735493374, 3542610091, 17155811156, 83480667707, 407969449010, 2001479974330, 9853652529076, 48666276924852, 241059431701113, 1197237945360797, 5960804381552300
Offset: 0

Views

Author

Alois P. Heinz, Sep 07 2008

Keywords

Crossrefs

3rd column of A144042.
Cf. A316103.

Programs

  • Maple
    b:= ((proc(p) local b; b:= proc(n) option remember; `if`(n=0, 1,
            add(add(d*p(d), d=numtheory[divisors](j))*b(n-j), j=1..n)/n)
          end end)@@3)(a):
    a:= n-> b(n-1):
    seq(a(n), n=0..25);  # revised Alois P. Heinz, Aug 27 2018
  • Mathematica
    etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[ j]}]*b[n-j], {j, 1, n}]/n]; b]; A[n_, k_] := Module[{a, b, t}, b[1] = etr[a]; For[ t = 2, t <= k, t++, b[t] = etr[b[t-1]]]; a = Function[m, If[m == 1, 1, b[k][m-1]]]; a[n]]; Table[ A[n, 3], {n, 0, 30} ] (* Jean-François Alcover, Mar 05 2015, after Alois P. Heinz *)

A144036 Shifts left when Euler transform applied 4 times.

Original entry on oeis.org

0, 1, 1, 5, 19, 89, 410, 2052, 10440, 54874, 293549, 1597621, 8807766, 49107289, 276358791, 1567866228, 8957204966, 51486464912, 297548288251, 1727856600935, 10076859047404, 58996263573440, 346614270372761, 2042929868812385, 12076076910981403
Offset: 0

Views

Author

Alois P. Heinz, Sep 07 2008

Keywords

Crossrefs

4th column of A144042.
Cf. A316104.

Programs

  • Maple
    k:=4: with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; local d,j; if n=0 then 1 else add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n fi end end: a:='a': b[1]:=etr(a): for t from 2 to k do b[t]:= etr(b[t-1]) od: a:= n-> `if`(n<2,n,b[k](n-1)): seq(a(n), n=0..30);
  • Mathematica
    etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[ j]}]*b[n-j], {j, 1, n}]/n]; b]; A[n_, k_] := Module[{a, b, t}, b[1] = etr[a]; For[ t = 2, t <= k, t++, b[t] = etr[b[t-1]]]; a = Function[m, If[m == 1, 1, b[k][m-1]]]; a[n]]; Table[A[n, 4], {n, 0, 30} ] (* Jean-François Alcover, Mar 05 2015, after Alois P. Heinz *)

A144037 Shifts left when Euler transform applied 5 times.

Original entry on oeis.org

0, 1, 1, 6, 26, 141, 751, 4337, 25512, 154839, 956877, 6014098, 38292603, 246550449, 1602304287, 10497348917, 69253008919, 459673679526, 3067621127220, 20570132531365, 138528107124822, 936524246563021, 6353624897677005, 43242243814689566, 295161330408772329
Offset: 0

Views

Author

Alois P. Heinz, Sep 07 2008

Keywords

Crossrefs

5th column of A144042.
Cf. A316105.

Programs

  • Maple
    k:=5: with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; local d,j; if n=0 then 1 else add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n fi end end: a:='a': b[1]:=etr(a): for t from 2 to k do b[t]:= etr(b[t-1]) od: a:= n-> `if`(n<2,n,b[k](n-1)): seq(a(n), n=0..30);
  • Mathematica
    etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[ j]}]*b[n-j], {j, 1, n}]/n]; b]; A[n_, k_] := Module[{a, b, t}, b[1] = etr[a]; For[ t = 2, t <= k, t++, b[t] = etr[b[t-1]]]; a = Function[m, If[m == 1, 1, b[k][m - 1]]]; a[n]]; Table[A[n, 5], {n, 0, 30} ] (* Jean-François Alcover, Mar 05 2015, after Alois P. Heinz *)

A144038 Shifts left when Euler transform applied 6 times.

Original entry on oeis.org

0, 1, 1, 7, 34, 209, 1260, 8219, 54677, 374904, 2617996, 18588586, 133708072, 972484206, 7139186644, 52832157095, 393700752053, 2951755132720, 22250074031893, 168524281244364, 1281906305775734, 9788771511218660, 75010092629043843, 576625427728255451
Offset: 0

Views

Author

Alois P. Heinz, Sep 07 2008

Keywords

Crossrefs

6th column of A144042.
Cf. A316106.

Programs

  • Maple
    k:=6: with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; local d,j; if n=0 then 1 else add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n fi end end: a:='a': b[1]:=etr(a): for t from 2 to k do b[t]:= etr(b[t-1]) od: a:= n-> `if`(n<2,n,b[k](n-1)): seq(a(n), n=0..30);
  • Mathematica
    etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[ j]}]*b[n-j], {j, 1, n}]/n]; b]; A[n_, k_] := Module[{a, b, t}, b[1] = etr[a]; For[ t = 2, t <= k, t++, b[t] = etr[b[t-1]]]; a = Function[m, If[m == 1, 1, b[k][m - 1]]]; a[n]]; Table[A[n, 6], {n, 0, 30} ] (* Jean-François Alcover, Mar 05 2015, after Alois P. Heinz *)

A144039 Shifts left when Euler transform applied 7 times.

Original entry on oeis.org

0, 1, 1, 8, 43, 295, 1982, 14379, 106464, 811769, 6304231, 49770106, 398042059, 3218655532, 26269422252, 216121646661, 1790428656802, 14922986525284, 125050910828179, 1052916751167676, 8903502888220215, 75579379572985970, 643818145873489913
Offset: 0

Views

Author

Alois P. Heinz, Sep 07 2008

Keywords

Crossrefs

7th column of A144042.
Cf. A316107.

Programs

  • Maple
    k:=7: with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; local d,j; if n=0 then 1 else add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n fi end end: a:='a': b[1]:=etr(a): for t from 2 to k do b[t]:= etr(b[t-1]) od: a:= n-> `if`(n<2,n,b[k](n-1)): seq(a(n), n=0..30);
  • Mathematica
    k = 7; etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[j]}]*b[n-j], {j, 1, n}]/n]; b]; b[1] = etr[a]; For[t = 2, t <= k, t++, b[t] = etr[b[t-1]]]; a[n_] := If[n<2, n, b[k][n-1]]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Mar 09 2015, after Alois P. Heinz *)

A144040 Shifts left when Euler transform applied 8 times.

Original entry on oeis.org

0, 1, 1, 9, 53, 401, 2967, 23659, 192615, 1613687, 13769538, 119419761, 1049154071, 9318828138, 83541286988, 754920397795, 6869170162829, 62884110339333, 578768613062948, 5352307127138701, 49708821972158231, 463445557084360740, 4335898935627480699
Offset: 0

Views

Author

Alois P. Heinz, Sep 07 2008

Keywords

Crossrefs

8th column of A144042.
Cf. A316108.

Programs

  • Maple
    k:=8: with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; local d,j; if n=0 then 1 else add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n fi end end: a:='a': b[1]:=etr(a): for t from 2 to k do b[t]:= etr(b[t-1]) od: a:= n-> `if`(n<2,n,b[k](n-1)): seq(a(n), n=0..30);
  • Mathematica
    k = 8; etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[j]}]*b[n-j], {j, 1, n}]/n]; b]; b[1] = etr[a]; For[t = 2, t <= k, t++, b[t] = etr[b[t-1]]]; a[n_] := If[n<2, n, b[k][n-1]]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Mar 09 2015, after Alois P. Heinz *)

A144041 Shifts left when Euler transform applied 9 times.

Original entry on oeis.org

0, 1, 1, 10, 64, 529, 4270, 37078, 328765, 2997844, 27840748, 262746590, 2511753957, 24274552279, 236771528856, 2327857190814, 23045073461778, 229523320443974, 2298252776303916, 23122596000124215, 233629865440550370, 2369682121825700424, 24119295413989862382
Offset: 0

Views

Author

Alois P. Heinz, Sep 07 2008

Keywords

Crossrefs

9th column of A144042.
Cf. A316109.

Programs

  • Maple
    k:=9: with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; local d,j; if n=0 then 1 else add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n fi end end: a:='a': b[1]:=etr(a): for t from 2 to k do b[t]:= etr(b[t-1]) od: a:= n-> `if`(n<2,n,b[k](n-1)): seq(a(n), n=0..30);
  • Mathematica
    k = 9; etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[j]}]*b[n-j], {j, 1, n}]/n]; b]; b[1] = etr[a]; For[t = 2, t <= k, t++, b[t] = etr[b[t-1]]]; a[n_] := If[n<2, n, b[k][n-1]]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Mar 09 2015, after Alois P. Heinz *)
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