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 1-5 of 5 results.

A047520 a(n) = 2*a(n-1) + n^2, a(0) = 0.

Original entry on oeis.org

0, 1, 6, 21, 58, 141, 318, 685, 1434, 2949, 5998, 12117, 24378, 48925, 98046, 196317, 392890, 786069, 1572462, 3145285, 6290970, 12582381, 25165246, 50331021, 100662618, 201325861, 402652398, 805305525, 1610611834, 3221224509
Offset: 0

Views

Author

Henry Bottomley, Jul 04 2000

Keywords

Comments

Convolution of squares (A000290) and powers of 2 (A000079). - Graeme McRae, Jun 07 2006
Antidiagonal sums of the convolution array A213568. - Clark Kimberling, Jun 18 2012
This is the partial sums of A050488. - J. M. Bergot, Oct 01 2012
From Peter Bala, Nov 29 2012: (Start)
This is the case m = 2 of the recurrence a(n) = m*a(n-1) + n^m, m = 1,2,..., with a(0) = 0.
The recurrence has the solution a(n) = m^n*Sum_{i=1..n} i^m/m^i and has the o.g.f. A(m,x)/((1-m*x)*(1-x)^(m+1)), where A(m,x) denotes the m-th Eulerian polynomial of A008292.
For other cases see A000217 (m = 1), A066999 (m = 3) and A067534 (m = 4).
(End)
Convolution of A000225 with A005408. - J. M. Bergot, Sep 19 2017

Crossrefs

Programs

  • GAP
    List([0..30], n-> 6*2^n -(n^2+4*n+6)); # G. C. Greubel, Jul 25 2019
  • Haskell
    a047520 n = sum $ zipWith (*)
                      (reverse $ take n $ tail a000290_list) a000079_list
    -- Reinhard Zumkeller, Nov 30 2012
    
  • Magma
    [ 6*2^n-n^2-4*n-6: n in [0..30]]; // Vincenzo Librandi, Aug 22 2011
    
  • Mathematica
    RecurrenceTable[{a[0]==0,a[n]==2a[n-1]+n^2},a[n],{n,30}] (* or *) LinearRecurrence[{5,-9,7,-2},{0,1,6,21},31] (* Harvey P. Dale, Aug 21 2011 *)
    f[n_]:= 2^n*Sum[i^2/2^i, {i, n}]; Array[f, 30] (* Robert G. Wilson v, Nov 28 2012 *)
  • PARI
    vector(30, n, n--; 6*2^n -(n^2+4*n+6)) \\ G. C. Greubel, Jul 25 2019
    
  • Sage
    [6*2^n -(n^2+4*n+6) for n in (0..30)] # G. C. Greubel, Jul 25 2019
    

Formula

a(n) = 6*2^n - n^2 - 4*n - 6 = 6*A000225(n) - A028347(n+2).
a(n) = 2^n*Sum_{i=1..n} i^2 / 2^i. - Benoit Cloitre, Jan 27 2002
a(0)=0, a(1)=1, a(2)=6, a(3)=21, a(n) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4). - Harvey P. Dale, Aug 21 2011
G.f.: x*(1+x)/((1-x)^3*(1-2*x)). - Harvey P. Dale, Aug 21 2011
a(n) = Sum_{k=0..n-1} A000079(n-k) * A000290(k). - Reinhard Zumkeller, Nov 30 2012
E.g.f.: 6*exp(2*x) -(6 +5*x +x^2)*exp(x). - G. C. Greubel, Jul 25 2019

A067534 a(n) = 4^n * Sum_{i=1..n} i^4/4^i.

Original entry on oeis.org

1, 20, 161, 900, 4225, 18196, 75185, 304836, 1225905, 4913620, 19669121, 78697220, 314817441, 1259308180, 5037283345, 20149198916, 80596879185, 322387621716, 1289550617185, 5158202628740, 20632810709441
Offset: 1

Views

Author

Benoit Cloitre, Jan 27 2002

Keywords

Crossrefs

Programs

  • Mathematica
    Table[4^n*Sum[i^4/4^i,{i,n}], {n,30}] (* or *) LinearRecurrence[ {9,-30,50,-45,21,-4}, {1,20,161,900,4225,18196}, 30] (* Harvey P. Dale, Jul 15 2012 *)

Formula

a(n) = 1/81 * (380*4^n - 27*n^4 - 144*n^3 - 360*n^2 - 528*n - 380). - Ralf Stephan, May 08 2004
a(1)=1, a(2)=20, a(3)=161, a(4)=900, a(5)=4225, a(6)=18196, a(n)= 9*a(n-1)- 30*a(n-2)+50*a(n-3)-45*a(n-4)+21*a(n-5)-4*a(n-6). - Harvey P. Dale, Jul 15 2012
From Peter Bala, Nov 29 2012: (Start)
Recurrence equation: a(n) = 4*a(n-1) + n^4. See A047520 and A066999.
O.g.f.: (x + 11*x^2 + 11*x^3 + x^4)/((1 - 4*x)*(1 - x)^5) = x + 20*x^2 + 161*x^3 + .... (End)

A218376 a(n) = 5^n*sum_{i=1..n} i^5/5^i.

Original entry on oeis.org

0, 1, 37, 428, 3164, 18945, 102501, 529312, 2679328, 13455689, 67378445, 337053276, 1685515212, 8427947353, 42140274589, 210702132320, 1053511710176, 5267559970737, 26337801743253, 131689011192364, 658445059161820
Offset: 0

Views

Author

Robert G. Wilson v, Nov 28 2012

Keywords

Crossrefs

Programs

  • Mathematica
    f[n_] := 5^n*Sum[i^5/5^i, {i, n}]; Array[f, 30, 0]

Formula

From Peter Bala, Nov 29 2012: (Start)
a(n) = 1/512*(3535*5^n - (128*n^5 + 800*n^4 + 2400*n^3 + 4600*n^2 + 5700*n + 3535)).
Recurrence equation: a(n) = 5*a(n-1) + n^5.
G.f.: (x + 26*x^2 + 66*x^3 + 26*x^4 + x^5)/((1 - 5*x)*(1 - x)^6) = x + 37*x^2 + 428*x^3 + ....
(End)

A368504 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = Sum_{j=0..n} k^(n-j) * j^k.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 6, 6, 1, 0, 1, 11, 21, 10, 1, 0, 1, 20, 60, 58, 15, 1, 0, 1, 37, 161, 244, 141, 21, 1, 0, 1, 70, 428, 900, 857, 318, 28, 1, 0, 1, 135, 1149, 3164, 4225, 2787, 685, 36, 1, 0, 1, 264, 3132, 10990, 18945, 18196, 8704, 1434, 45, 1
Offset: 0

Views

Author

Seiichi Manyama, Dec 27 2023

Keywords

Examples

			Square array begins:
  1,  0,   0,    0,     0,      0,      0, ...
  1,  1,   1,    1,     1,      1,      1, ...
  1,  3,   6,   11,    20,     37,     70, ...
  1,  6,  21,   60,   161,    428,   1149, ...
  1, 10,  58,  244,   900,   3164,  10990, ...
  1, 15, 141,  857,  4225,  18945,  81565, ...
  1, 21, 318, 2787, 18196, 102501, 536046, ...
		

Crossrefs

Columns k=0..5 give A000012, A000217, A047520, A066999, A067534, A218376.
Main diagonal gives A368505.
Cf. A368486.

Programs

  • PARI
    T(n, k) = sum(j=0, n, k^(n-j)*j^k);

Formula

G.f. of column k: x*A_k(x)/((1-k*x) * (1-x)^(k+1)), where A_n(x) are the Eulerian polynomials for k > 0.
T(0,k) = 0^k; T(n,k) = k*T(n-1,k) + n^k.

A368530 a(n) = Sum_{k=1..n} k^3 * 4^(n-k).

Original entry on oeis.org

0, 1, 12, 75, 364, 1581, 6540, 26503, 106524, 426825, 1708300, 6834531, 27339852, 109361605, 437449164, 1749800031, 6999204220, 27996821793, 111987293004, 447949178875, 1791796723500, 7167186903261, 28668747623692, 114674990506935, 458699962041564
Offset: 0

Views

Author

Seiichi Manyama, Dec 29 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=1, n, k^3*4^(n-k));

Formula

G.f.: x * (1+4*x+x^2)/((1-4*x) * (1-x)^4).
a(n) = 8*a(n-1) - 22*a(n-2) + 28*a(n-3) - 17*a(n-4) + 4*a(n-5).
a(n) = (11*4^(n+1) - (9*n^3 + 36*n^2 + 60*n + 44))/27.
a(0) = 0; a(n) = 4*a(n-1) + n^3.
Showing 1-5 of 5 results.