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 1-7 of 7 results.

A081144 Starting at 1, four-fold convolution of A000400 (powers of 6).

Original entry on oeis.org

0, 0, 0, 1, 24, 360, 4320, 45360, 435456, 3919104, 33592320, 277136640, 2217093120, 17293326336, 132058128384, 990435962880, 7313988648960, 53287631585280, 383670947414016, 2733655500324864, 19296391766999040, 135074742368993280
Offset: 0

Views

Author

Paul Barry, Mar 08 2003

Keywords

Comments

With a different offset, number of n-permutations (n=4) of 7 objects: t, u, v, w, z, x, y with repetition allowed, containing exactly three u's. Example: a(4)=24 because we have uuut, uutu, utuu, tuuu, uuuv, uuvu, uvuu, vuuu, uuuw, uuwu, uwuu, wuuu, uuuz, uuzu, uzuu, zuuu, uuux, uuxu, uxuu, xuuu, uuuy, uuyu, uyuu, yuuu. - Zerinvary Lajos, Jun 03 2008

Crossrefs

Programs

  • GAP
    List([-3..18],n->Binomial(n+3,3)*6^n); # Muniru A Asiru, Feb 19 2018
  • Magma
    [6^n* Binomial(n+3, 3): n in [-3..20]]; // Vincenzo Librandi, Oct 16 2011
    
  • Maple
    seq(seq(binomial(i+2, j)*6^(i-1), j =i-1), i=-2..19); # Zerinvary Lajos, Dec 30 2007
    seq(binomial(n+3,3)*6^n,n=-3..18); # Zerinvary Lajos, Jun 03 2008
  • Sage
    [lucas_number2(n, 6, 0)*binomial(n,3)/6^3 for n in range(0, 22)] # Zerinvary Lajos, Mar 13 2009
    

Formula

G.f.: x^3/(1 - 6*x)^4.
a(n) = 24*a(n-1) - 216*a(n-2) + 864*a(n-3) - 1296*a(n-4) for n > 3, a(0) = a(1) = a(2) = 0, a(3) = 1.
a(n) = 6^(n - 3)*binomial(n, 3).
From Amiram Eldar, Jan 04 2022: (Start)
Sum_{n>=3} 1/a(n) = 450*log(6/5) - 81.
Sum_{n>=3} (-1)^(n+1)/a(n) = 882*log(7/6) - 135. (End)

A128963 a(n) = (n^3 - n)*5^n.

Original entry on oeis.org

0, 150, 3000, 37500, 375000, 3281250, 26250000, 196875000, 1406250000, 9667968750, 64453125000, 418945312500, 2666015625000, 16662597656250, 102539062500000, 622558593750000, 3735351562500000, 22178649902343750, 130462646484375000, 761032104492187500
Offset: 1

Views

Author

Mohammad K. Azarian, Apr 28 2007

Keywords

Crossrefs

Programs

  • Magma
    [(n^3-n)*5^n: n in [1..25]]; // Vincenzo Librandi, Feb 12 2013
  • Mathematica
    Table[(n^3-n)5^n,{n,20}] (* or *) LinearRecurrence[{20,-150,500,-625},{0,150,3000,37500},20] (* Harvey P. Dale, Jul 22 2012 *)
    CoefficientList[Series[150 x/(1 - 5 x)^4, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 12 2013 *)

Formula

a(1)=0, a(2)=150, a(3)=3000, a(4)=37500, a(n)=20*a(n-1)-150*a(n-2)+ 500*a(n-3)- 625*a(n-4). - Harvey P. Dale, Jul 22 2012
G.f.: 150*x^2/(1 - 5*x)^4. - Vincenzo Librandi, Feb 12 2013
a(n) = 150*A081143(n+1). - Bruno Berselli, Feb 12 2013
From Amiram Eldar, Oct 02 2022: (Start)
a(n) = A007531(n+1)*A000351(n).
Sum_{n>=2} 1/a(n) = (8/5)*log(5/4) - 7/20.
Sum_{n>=2} (-1)^n/a(n) = (18/5)*log(6/5) - 13/20. (End)

Extensions

Offset corrected by Mohammad K. Azarian, Nov 20 2008

A038243 Triangle whose (i,j)-th entry is 5^(i-j)*binomial(i,j).

Original entry on oeis.org

1, 5, 1, 25, 10, 1, 125, 75, 15, 1, 625, 500, 150, 20, 1, 3125, 3125, 1250, 250, 25, 1, 15625, 18750, 9375, 2500, 375, 30, 1, 78125, 109375, 65625, 21875, 4375, 525, 35, 1, 390625, 625000, 437500, 175000, 43750, 7000, 700, 40, 1, 1953125, 3515625, 2812500, 1312500, 393750, 78750, 10500, 900, 45, 1
Offset: 0

Views

Author

Keywords

Comments

Mirror image of A013612. - Zerinvary Lajos, Nov 25 2007
T(i,j) is the number of i-permutations of 6 objects a,b,c,d,e,f, with repetition allowed, containing j a's. - Zerinvary Lajos, Dec 21 2007
Triangle of coefficients in expansion of (5+x)^n - N-E. Fahssi, Apr 13 2008
Also the convolution triangle of A000351. - Peter Luschny, Oct 09 2022

Examples

			Triangle begins as:
       1;
       5,      1;
      25,     10,      1;
     125,     75,     15,      1;
     625,    500,    150,     20,     1;
    3125,   3125,   1250,    250,    25,    1;
   15625,  18750,   9375,   2500,   375,   30,   1;
   78125, 109375,  65625,  21875,  4375,  525,  35,  1;
  390625, 625000, 437500, 175000, 43750, 7000, 700, 40, 1;
		

Crossrefs

Sequences of the form q^(n-k)*binomial(n, k): A007318 (q=1), A038207 (q=2), A027465 (q=3), A038231 (q=4), this sequence (q=5), A038255 (q=6), A027466 (q=7), A038279 (q=8), A038291 (q=9), A038303 (q=10), A038315 (q=11), A038327 (q=12), A133371 (q=13), A147716 (q=14), A027467 (q=15).

Programs

  • Magma
    [5^(n-k)*Binomial(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, May 12 2021
    
  • Maple
    for i from 0 to 8 do seq(binomial(i, j)*5^(i-j), j = 0 .. i) od; # Zerinvary Lajos, Dec 21 2007
    # Uses function PMatrix from A357368. Adds column 1, 0, 0, ... to the left.
    PMatrix(10, n -> 5^(n-1)); # Peter Luschny, Oct 09 2022
  • Mathematica
    With[{q=5}, Table[q^(n-k)*Binomial[n,k], {n,0,12}, {k,0,n}]//Flatten] (* G. C. Greubel, May 12 2021 *)
  • Sage
    flatten([[5^(n-k)*binomial(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, May 12 2021

Formula

See A038207 and A027465 and replace 2 and 3 in analogous formulas with 5. - Tom Copeland, Oct 26 2012

A218016 Triangle, read by rows, where T(n,k) = k!*C(n, k)*5^(n-k) for n>=0, k=0..n.

Original entry on oeis.org

1, 5, 1, 25, 10, 2, 125, 75, 30, 6, 625, 500, 300, 120, 24, 3125, 3125, 2500, 1500, 600, 120, 15625, 18750, 18750, 15000, 9000, 3600, 720, 78125, 109375, 131250, 131250, 105000, 63000, 25200, 5040, 390625, 625000, 875000, 1050000, 1050000, 840000, 504000, 201600, 40320
Offset: 0

Views

Author

Vincenzo Librandi, Nov 10 2012

Keywords

Comments

Triangle formed by the derivatives of x^n evaluated at x=5.
Sum(T(n,k), k=0..n) = A080954(n) (see the Formula section of A080954). . Also:
first column: A000351;
second column: A053464;
third column: 2*A084902;
fourth column: 6*A081143.

Examples

			Triangle begins:
1;
5,      1;
25,     10,     2;
125,    75,     30,     6;
625,    500,    300,    120,     24;
3125,   3125,   2500,   1500,    600,     120;
15625,  18750,  18750,  15000,   9000,    3600,   720;
78125,  109375, 131250, 131250,  105000,  63000,  25200,  5040;
390625, 625000, 875000, 1050000, 1050000, 840000, 504000, 201600, 40320; etc.
		

Crossrefs

Programs

  • Magma
    [Factorial(n)/Factorial(n-k)*5^(n-k): k in [0..n], n in [0..10]];
  • Mathematica
    Flatten[Table[n!/(n-k)!*5^(n-k), {n, 0, 10}, {k, 0, n}]]

Formula

T(n,k) = 5^(n-k)*n!/(n-k)! for n>=0, k=0..n.
E.g.f. (by columns): exp(5x)*x^k.

A305837 Triangle read by rows: T(0,0) = 1; T(n,k) = 5*T(n-1,k) + T(n-2,k-1) for k = 0..floor(n/2); T(n,k)=0 for n or k < 0.

Original entry on oeis.org

1, 5, 25, 1, 125, 10, 625, 75, 1, 3125, 500, 15, 15625, 3125, 150, 1, 78125, 18750, 1250, 20, 390625, 109375, 9375, 250, 1, 1953125, 625000, 65625, 2500, 25, 9765625, 3515625, 437500, 21875, 375, 1, 48828125, 19531250, 2812500, 175000, 4375, 30, 244140625, 107421875, 17578125, 1312500, 43750, 525, 1
Offset: 0

Views

Author

Shara Lalo, Jun 11 2018

Keywords

Comments

The numbers in rows of the triangle are along skew diagonals pointing top-left in center-justified triangle given in A013612 ((1+5*x)^n).
The coefficients in the expansion of 1/(1-5x-x^2) are given by the sequence generated by the row sums.
If s(n) is the row sum at n, then the ratio s(n)/s(n-1) is approximately 5.1925824035..., a metallic mean (see A098318), when n approaches infinity.

Examples

			Triangle begins:
            1;
            5;
           25,           1;
          125,          10;
          625,          75,          1;
         3125,         500,         15;
        15625,        3125,        150,         1;
        78125,       18750,       1250,        20;
       390625,      109375,       9375,       250,        1;
      1953125,      625000,      65625,      2500,       25;
      9765625,     3515625,     437500,     21875,      375,      1;
     48828125,    19531250,    2812500,    175000,     4375,     30;
    244140625,   107421875,   17578125,   1312500,    43750,    525,     1;
   1220703125,   585937500,  107421875,   9375000,   393750,   7000,    35;
   6103515625,  3173828125,  644531250,  64453125,  3281250,  78750,   700,  1;
  30517578125, 17089843750, 3808593750, 429687500, 25781250, 787500, 10500, 40;
		

References

  • Shara Lalo and Zagros Lalo, Polynomial Expansion Theorems and Number Triangles, Zana Publishing, 2018, ISBN: 978-1-9995914-0-3, pp. 70, 72, 92, 380, 382.

Crossrefs

Row sums give A052918.
Cf. A000351 (column 0), A053464 (column 1), A081135 (column 2), A081143 (column 3), A036071 (column 4).
Cf. A013612.
Cf. A098318.

Programs

  • Mathematica
    t[0, 0] = 1; t[n_, k_] := If[n < 0 || k < 0, 0, 5 t[n - 1, k] + t[n - 2, k - 1]]; Table[t[n, k], {n, 0, 12}, {k, 0, Floor[n/2]}] // Flatten

Formula

G.f.: 1/(1 - 5*t*x - t^2).

A129005 a(n) = (n^3 + n^2)*5^n.

Original entry on oeis.org

0, 10, 300, 4500, 50000, 468750, 3937500, 30625000, 225000000, 1582031250, 10742187500, 70898437500, 457031250000, 2888183593750, 17944335937500, 109863281250000, 664062500000000, 3968811035156250, 23483276367187500
Offset: 0

Views

Author

Mohammad K. Azarian, May 01 2007

Keywords

Crossrefs

Programs

  • Magma
    [(n^3+n^2)*5^n: n in [0..25]]; // Vincenzo Librandi, Feb 12 2013
    
  • Magma
    I:=[0,10,300,4500]; [n le 4 select I[n] else 20*Self(n-1)-150*Self(n-2)+500*Self(n-3)-625*Self(n-4): n in [1..25]]; // Vincenzo Librandi, Feb 12 2013
    
  • Mathematica
    CoefficientList[Series[10 x (1 + 10 x)/(1 - 5 x)^4, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 12 2013 *)
    Table[(n^3+n^2)5^n,{n,0,30}] (* or *) LinearRecurrence[{20,-150,500,-625},{0,10,300,4500},30] (* Harvey P. Dale, May 15 2022 *)
  • PARI
    A129005(n)=5^n*(1+n)*n^2 \\ - M. F. Hasler, Feb 12 2013

Formula

G.f.: 10*x*(1 + 10*x)/(1 - 5*x)^4. - Vincenzo Librandi, Feb 12 2013
a(n) = 20*a(n-1)-150*a(n-2)+500*a(n-3)-625*a(n-4). - Vincenzo Librandi, Feb 12 2013
a(n) = 10*A081143(n+2)+100*A081143(n+1). - Bruno Berselli, Feb 13 2013

Extensions

Initial term a(0)=0 added by M. F. Hasler, Feb 12 2013

A173113 a(n) = binomial(n + 10, 10) * 5^n.

Original entry on oeis.org

1, 55, 1650, 35750, 625625, 9384375, 125125000, 1519375000, 17092968750, 180425781250, 1804257812500, 17222460937500, 157872558593750, 1396564941406250, 11970556640625000, 99754638671875000
Offset: 0

Views

Author

Zerinvary Lajos, Feb 10 2010

Keywords

Comments

With a different offset, number of n-permutations (n>=10) of 6 objects: t, u, v, z, x, y with repetition allowed, containing exactly ten (10) u's.

Crossrefs

Programs

  • Magma
    [5^n*Binomial(n+10, 10): n in [0..30]]; // Vincenzo Librandi, Oct 15 2011
  • Mathematica
    Table[Binomial[n + 10, 10]*5^n, {n, 0, 20}]

Formula

a(n) = C(n + 10, 10)*5^n, n>=0.
G.f.: 1/(1-5*x)^11. - Vincenzo Librandi, Oct 15 2011
From Amiram Eldar, Sep 01 2022: (Start)
Sum_{n>=0} 1/a(n) = 184261655/63 - 13107200*log(5/4).
Sum_{n>=0} (-1)^n/a(n) = 503884800*log(6/5) - 11575501585/126. (End)
Showing 1-7 of 7 results.