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.

A260987 Record values in A008480.

Original entry on oeis.org

1, 2, 3, 4, 6, 12, 20, 30, 60, 105, 120, 140, 180, 210, 280, 420, 504, 840, 1120, 1512, 1680, 2520, 3780, 5040, 6300, 7560, 9240, 12600, 13860, 15120, 15840, 27720, 34650, 37800, 55440, 83160, 102960, 110880, 138600, 180180, 205920, 216216, 240240, 332640
Offset: 1

Views

Author

Reinhard Zumkeller, Nov 18 2015

Keywords

Examples

			.   n | x = A260633(n)        | y = a(n)             | [x/y] | x mod y
. ----+-----------------------+----------------------+-------+---------
.   1 |     1 | 1             |    1 | 1             |    1  |      0
.   2 |     6 | 2*3           |    2 | 2             |    3  |      0
.   3 |    12 | 2^2*3         |    3 | 3             |    4  |      0
.   4 |    24 | 2^3*3         |    4 | 2^2           |    6  |      0
.   5 |    30 | 2*3*5         |    6 | 2*3           |    5  |      0
.   6 |    60 | 2^2*3*5       |   12 | 2^2*3         |    5  |      0
.   7 |   120 | 2^3*3*5       |   20 | 2^2*5         |    6  |      0
.   8 |   180 | 2^2*3^2*5     |   30 | 2*3*5         |    6  |      0
.   9 |   360 | 2^3*3^2*5     |   60 | 2^2*3*5       |    6  |      0
.  10 |   720 | 2^4*3^2*5     |  105 | 3*5*7         |    6  |     90
.  11 |   840 | 2^3*3*5*7     |  120 | 2^3*3*5       |    7  |      0
.  12 |  1080 | 2^3*3^3*5     |  140 | 2^2*5*7       |    7  |    100
.  13 |  1260 | 2^2*3^2*5*7   |  180 | 2^2*3^2*5     |    7  |      0
.  14 |  1680 | 2^4*3*5*7     |  210 | 2*3*5*7       |    8  |      0
.  15 |  2160 | 2^4*3^3*5     |  280 | 2^3*5*7       |    7  |    200
.  16 |  2520 | 2^3*3^2*5*7   |  420 | 2^2*3*5*7     |    6  |      0
.  17 |  4320 | 2^5*3^3*5     |  504 | 2^3*3^2*7     |    8  |    288
.  18 |  5040 | 2^4*3^2*5*7   |  840 | 2^3*3*5*7     |    6  |      0
.  19 |  7560 | 2^3*3^3*5*7   | 1120 | 2^5*5*7       |    6  |    840
.  20 | 10080 | 2^5*3^2*5*7   | 1512 | 2^3*3^3*7     |    6  |   1008
.  21 | 12600 | 2^3*3^2*5^2*7 | 1680 | 2^4*3*5*7     |    7  |    840
.  22 | 15120 | 2^4*3^3*5*7   | 2520 | 2^3*3^2*5*7   |    6  |      0
.  23 | 25200 | 2^4*3^2*5^2*7 | 3780 | 2^2*3^3*5*7   |    6  |   2520
.  24 | 30240 | 2^5*3^3*5*7   | 5040 | 2^4*3^2*5*7   |    6  |      0
.  25 | 45360 | 2^4*3^4*5*7   | 6300 | 2^2*3^2*5^2*7 |    7  |   1260 .
		

Crossrefs

Programs

  • Haskell
    a260987 n = a260987_list !! (n-1)
    (a260987_list, a260633_list) = unzip $ f 1 0 where
       f x r = if y > r then (y, x) : f (x + 1) y else f (x + 1) r
               where y = a008480 x

Formula

a(n) = A008480(A260633(n)).