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 1-9 of 9 results.

A067411 Third column of triangle A067410 and second column of A067417.

Original entry on oeis.org

1, 4, 24, 144, 864, 5184, 31104, 186624, 1119744, 6718464, 40310784, 241864704, 1451188224, 8707129344, 52242776064, 313456656384, 1880739938304, 11284439629824, 67706637778944, 406239826673664
Offset: 0

Views

Author

Wolfdieter Lang, Jan 25 2002

Keywords

Comments

Let f(k) be the sum of the smallest three positive divisors of k, g(k) be the sum of the largest two positive divisors of k, this sequence from a(2) onwards contains the numbers k for which g(k) is a positive integer power of f(k). - Yifan Xie, Jan 27 2024

Crossrefs

A002001, A067412 (second and fourth column of A067410), A000244, A067403 (first and third column of A067417), A000400 (powers of 6).
Row sums of A038195.

Programs

  • Mathematica
    CoefficientList[Series[(1-2x)/(1-6x),{x,0,30}],x] (* Harvey P. Dale, Feb 26 2015 *)
  • PARI
    a(n) = if(n<=0, 0, 4*6^(n-1) ); \\ Joerg Arndt, Feb 23 2014

Formula

a(n) = A067410(n+2, 2) = A067417(n+1, 1).
a(n) = 4 * 6^(n-1), for n >= 1, a(0)=1.
G.f.: (1-2*x)/(1-6*x).
E.g.f.: (2*exp(6*x)+1) / 3 = exp(3*x)*(cosh(3*x) + sinh(3*x)/3). - Paul Barry, Nov 20 2003
a(n) = Sum_{k=0..n} C(n,k) * A001045(n+k+1). - Paul Barry, Apr 19 2010

Extensions

Incorrect formula deleted by Harvey P. Dale, Feb 26 2015
Formula restored by Sean A. Irvine, Jan 10 2021

A067412 Fourth column of triangle A067410.

Original entry on oeis.org

1, 5, 40, 320, 2560, 20480, 163840, 1310720, 10485760, 83886080, 671088640, 5368709120, 42949672960, 343597383680, 2748779069440, 21990232555520, 175921860444160, 1407374883553280, 11258999068426240
Offset: 0

Views

Author

Wolfdieter Lang, Jan 25 2002

Keywords

Comments

The fifth column gives [1,6,60,600,6000,60000,...].
a(n+1) = A157176(A016957(n)). [From Reinhard Zumkeller, Feb 24 2009]

Crossrefs

Cf. A067411 (third column), A067413 (sixth column), A001018 (powers of 8).

Programs

  • Mathematica
    Join[{1},NestList[8#&,5,20]] (* or *) CoefficientList[Series[ (1-3x)/ (1-8x),{x,0,20}],x] (* Harvey P. Dale, May 14 2011 *)

Formula

a(n)= A067410(n+3, 3). a(n)= 5*8^(n-1), n>=1, a(0)=1.
G.f.: (1-3*x)/(1-8*x).
E.g.f.: (5*exp(8*x)+3)/8 = exp(4*x)*(cosh(4*x)+sinh(4*x)/4) - Paul Barry, Nov 20 2003

A067413 Sixth column of triangle A067410.

Original entry on oeis.org

1, 7, 84, 1008, 12096, 145152, 1741824, 20901888, 250822656, 3009871872, 36118462464, 433421549568, 5201058594816, 62412703137792, 748952437653504, 8987429251842048, 107849151022104576, 1294189812265254912
Offset: 0

Views

Author

Wolfdieter Lang, Jan 25 2002

Keywords

Comments

The fifth column is [1,6,60,600,6000,60000,...].

Crossrefs

Cf. A067412 (fourth column), A067414 (seventh column), A001021 (powers of 12).

Formula

a(n)= A067410(n+5, 5). a(n)= 7*12^(n-1), n>=1, a(0)=1.
G.f.: (1-5*x)/(1-12*x).

A067414 Seventh column of triangle A067410.

Original entry on oeis.org

1, 8, 112, 1568, 21952, 307328, 4302592, 60236288, 843308032, 11806312448, 165288374272, 2314037239808, 32396521357312, 453551299002368, 6349718186033152, 88896054604464128, 1244544764462497792
Offset: 0

Views

Author

Wolfdieter Lang, Jan 25 2002

Keywords

Crossrefs

Cf. A067413 (sixth column), A067415 (eighth column), A001023 (powers of 14).

Formula

a(n) = A067410(n+6, 6).
a(n) = 8*14^(n-1), n>=1, a(0)=1.
G.f.: (1-6*x)/(1-14*x).

A067415 Eighth column of triangle A067410.

Original entry on oeis.org

1, 9, 144, 2304, 36864, 589824, 9437184, 150994944, 2415919104, 38654705664, 618475290624, 9895604649984, 158329674399744, 2533274790395904, 40532396646334464, 648518346341351424
Offset: 0

Views

Author

Wolfdieter Lang, Jan 25 2002

Keywords

Crossrefs

Cf. A067414 (seventh column), A067416 (ninth column), A001025 (powers of 16).

Formula

a(n)= A067410(n+7, 7). a(n)= 9*16^(n-1), n>=1, a(0)=1.
G.f.: (1-7*x)/(1-16*x).

A067416 Ninth column of triangle A067410.

Original entry on oeis.org

1, 10, 180, 3240, 58320, 1049760, 18895680, 340122240, 6122200320, 110199605760, 1983592903680, 35704672266240, 642684100792320, 11568313814261760, 208229648656711680, 3748133675820810240
Offset: 0

Views

Author

Wolfdieter Lang, Jan 25 2002

Keywords

Crossrefs

Cf. A067415 (eighth column), A001027 (powers of 18).

Formula

a(n)= A067410(n+8, 8). a(n)= 10*18^(n-1), n>=1, a(0)=1.
G.f. (1-8*x)/(1-18*x).

A067417 Triangle with columns built from certain power sequences.

Original entry on oeis.org

1, 3, 1, 9, 4, 1, 27, 24, 5, 1, 81, 144, 45, 6, 1, 243, 864, 405, 72, 7, 1, 729, 5184, 3645, 864, 105, 8, 1, 2187, 31104, 32805, 10368, 1575, 144, 9, 1, 6561, 186624, 295245, 124416, 23625, 2592, 189, 10, 1, 19683, 1119744, 2657205, 1492992, 354375, 46656, 3969, 240, 11, 1
Offset: 0

Views

Author

Wolfdieter Lang, Jan 25 2002

Keywords

Examples

			Triangle starts:
   1;
   3,  1;
   9,  4, 1;
  27, 24, 5, 1;
  ...
		

Crossrefs

Cf. A009998 (triangle built from powers of (m+1)), A067402, A067410.

Programs

  • Mathematica
    A[n_,m_]:=If[n==m,1,(m+3)(3(m+1))^(n-m-1)]; Flatten[Table[A[n,m],{n,0,9},{m,0,n}]] (* Stefano Spezia, Sep 30 2022 *)

Formula

a(n, m) = 1 if n = m; a(n, m) = (m+3)*(3*(m+1))^(n-m-1) if n > m >= 0.
G.f. for column m: (x^m)*(1-2*m*x)/(1-3*(m+1)*x).

A067425 Triangle with columns built from certain power sequences.

Original entry on oeis.org

1, 4, 1, 16, 5, 1, 64, 40, 6, 1, 256, 320, 72, 7, 1, 1024, 2560, 864, 112, 8, 1, 4096, 20480, 10368, 1792, 160, 9, 1, 16384, 163840, 124416, 28672, 3200, 216, 10, 1, 65536, 1310720, 1492992, 458752, 64000
Offset: 0

Views

Author

Wolfdieter Lang, Jan 25 2002

Keywords

Comments

The fifth column (m=4) gives [1, 8, 160, 3200, 64000, 1280000, 25600000, ...].

Examples

			Triangle starts:
   1;
   4,  1;
  16,  5,  1;
  64, 40,  6,  1;
  ...
		

Crossrefs

Columns 0..3 are A000302 (powers of 4), A067412, A067419, A067404.
Columns 5..8 are A067426, A067427, A067428, A067429.

Programs

  • Mathematica
    A067425[n_, m_] := If[n == m, 1, (m + 4)*(4*(m + 1))^(n - m - 1)];
    Table[A067425[n, m], {n, 0, 10}, {m, 0, n}] (* Paolo Xausa, Oct 16 2024 *)

Formula

T(n,m) = 1 if n = m; T(n,m) = (m+4)*(4*(m+1))^(n-m-1) if n > m >= 0, else 0.
G.f. for column m: (x^m)*(1-3*m*x)/(1-4*(m+1)*x).

A090019 a(n) = (3*10^n + 2*0^n)/5.

Original entry on oeis.org

1, 6, 60, 600, 6000, 60000, 600000, 6000000, 60000000, 600000000, 6000000000, 60000000000, 600000000000, 6000000000000, 60000000000000, 600000000000000, 6000000000000000, 60000000000000000, 600000000000000000
Offset: 0

Views

Author

Paul Barry, Nov 20 2003

Keywords

Comments

Fifth column of triangle A067410.

Programs

  • Mathematica
    Join[{1},NestList[10#&,6,20]] (* Harvey P. Dale, Apr 02 2015 *)

Formula

G.f.: (1-4x)/(1-10x).
E.g.f.: (3*exp(10x)+2)/5 = exp(5x)(cosh(5x)+sinh(5x)/5).
Showing 1-9 of 9 results.