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.

A079760 Denominator in the expression for a(n) in A079759.

Original entry on oeis.org

6, 12, 20, 28, 36, 45, 56, 70, 80, 90, 104, 112, 120, 132, 140, 154, 168, 180, 192, 208, 220, 234, 250, 264, 280, 297, 312, 324, 336, 350, 360, 378, 396, 416, 432, 448, 462, 480, 495, 504, 520, 539, 560, 576, 594, 612, 630, 640, 660, 672, 693, 714, 728, 748
Offset: 1

Views

Author

Amarnath Murthy, Jan 10 2003

Keywords

Examples

			A079759(1) = 1*2*3*4*5/6 hence a(1) = 6.

Crossrefs

Cf. A079759.

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)hotmail.com) and Sascha Kurz, Jan 12 2003

A109894 Duplicate of A079759.

Original entry on oeis.org

1, 20, 4620, 12697776, 159845400, 941432800, 158800433792, 1895312483064000, 3438271897004237230080, 933561026438040, 2562849175892544, 640904462719404383808000, 1528364130975, 2352733350786, 959393282698730880000, 6142080926952
Offset: 1

Views

Author

Keywords

A109895 Group the natural numbers so that every 2n-th group product is divisible by the single number in the next group. (1), (2,3,4,5), (6), (7,8,9,10,11), (12), (13,14,15,16,17,18,19),(20), (21,22,23,24,25,26,27),(28),... Sequence contains the single members of the odd numbered groups.

Original entry on oeis.org

1, 6, 12, 20, 28, 36, 45, 56, 70, 80, 90, 104, 112, 120, 132, 140, 154, 168, 180, 192, 208, 220, 234, 250, 264, 280, 297, 312, 324, 336, 350, 360, 378, 396, 416, 432, 448, 462, 480, 495, 504, 520, 539, 560, 576, 594, 612, 630, 640, 660, 672, 693, 714, 728, 748
Offset: 1

Views

Author

Amarnath Murthy, Jul 13 2005

Keywords

Comments

a(n) divides (a(n)-1)! / (a(n-1)!) and is the smallest integer with this property. - Simon Nickerson (simonn(AT)maths.bham.ac.uk), Jul 15 2005
Essentially a duplicate of A079760. - R. J. Mathar, Aug 18 2008

Crossrefs

Cf. A079759, A109896, A109897.

Programs

  • GAP
    A := [ 1 ]; n := 1; repeat p := 1; k := n + 1; repeat p := p * k; k := k+1; until p mod k = 0; n := k; Add(A, n); until n > 10000; # Simon Nickerson

Extensions

More terms from Simon Nickerson (simonn(AT)maths.bham.ac.uk), Jul 15 2005

A109896 Group the natural numbers so that every 2n-th group product is divisible by the single number in the next group. (1), (2,3,4,5), (6), (7,8,9,10,11), (12), (13,14,15,16,17,18,19),(20), (21,22,23,24,25,26,27),(28),... Sequence contains the number of terms in the 2n-th group.

Original entry on oeis.org

4, 5, 7, 7, 7, 8, 10, 13, 9, 9, 13, 7, 7, 11, 7, 13, 13, 11, 11, 15, 11, 13, 15, 13, 15, 16, 14, 11, 11, 13, 9, 17, 17, 19, 15, 15, 13, 17, 14, 8, 15, 18, 20, 15, 17, 17, 17, 9, 19, 11, 20, 20, 13, 19, 19, 15, 15, 9, 14, 14, 17, 16, 15, 18, 13, 20, 14, 14, 14, 17, 15, 15, 15, 21, 13
Offset: 1

Views

Author

Amarnath Murthy, Jul 13 2005

Keywords

Comments

a(n) = A109895(x+1)-A109895(x)-1 - Simon Nickerson (simonn(AT)maths.bham.ac.uk), Jul 15 2005

Crossrefs

Cf. A079759, A109895, A109897.

Extensions

More terms from Simon Nickerson (simonn(AT)maths.bham.ac.uk), Jul 15 2005

A109897 Group the natural numbers so that every 2n-th group product is divisible by the single number in the next group. (1), (2,3,4,5), (6), (7,8,9,10,11), (12), (13,14,15,16,17,18,19),(20), (21,22,23,24,25,26,27),(28),... Sequence contains the product of terms in the 2n-th group.

Original entry on oeis.org

120, 55440, 253955520, 4475671200, 33891580800, 7146019520640, 106137499051584000, 240679032790296606105600, 74684882115043200, 230656425830328960, 66654064122818055916032000, 171176782669200, 282328002094320, 126639913316232476160000, 859891329773280
Offset: 1

Views

Author

Amarnath Murthy, Jul 13 2005

Keywords

Examples

			a(2) = 7*8*9*10*11 = 55440.

Crossrefs

Cf. A079759, A109895, A109896.

Programs

  • PARI
    m=1;for(k=2,150,if(m%k==0,print1(m", ");m=1,m*=k))

Extensions

Terms from a(5) from Franklin T. Adams-Watters, Jun 26 2011
Showing 1-5 of 5 results.

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