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.

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A348582 a(n) is the greatest factor among all the products A307720(k) * A307720(k+1) equal to n.

Original entry on oeis.org

1, 2, 3, 2, 5, 3, 7, 4, 3, 5, 11, 4, 13, 7, 5, 8, 17, 6, 19, 5, 7, 11, 23, 8, 5, 13, 9, 7, 29, 6, 31, 8, 11, 17, 7, 9, 37, 19, 13, 8, 41, 7, 43, 11, 9, 23, 47, 8, 7, 10, 17, 13, 53, 9, 11, 8, 19, 29, 59, 10, 61, 31, 9, 8, 13, 11, 67, 17, 23, 10, 71, 9, 73, 37
Offset: 1

Views

Author

Rémy Sigrist and N. J. A. Sloane, Oct 24 2021

Keywords

Comments

We know there are n ways to get n as a product of terms A307720(k)*A307720(k+1) for various k's. Look at these 2*n numbers from A307720. Then a(n) is the largest of them.

Examples

			For n = 6:
- we have the following products equal to 6:
    A307720(7)  * A307720(8)  = 3 * 2 = 6
    A307720(12) * A307720(13) = 2 * 3 = 6
    A307720(13) * A307720(14) = 3 * 2 = 6
    A307720(14) * A307720(15) = 2 * 3 = 6
    A307720(15) * A307720(16) = 3 * 2 = 6
    A307720(16) * A307720(17) = 2 * 3 = 6
- the corresponding distinct factors are 2 and 3,
- hence a(6) = 3.

Links

Crossrefs

Cf. A307720, A307730, A348581.

Programs

  • C
    See Links section.

Formula

a(p) = p for any prime number p.
a(n) * A348581(n) = n.

A348254 Records in A348409.

Original entry on oeis.org

1, 3, 6, 11, 51, 58, 69, 1384, 1397, 3754, 3773, 6702, 6731, 84656, 84693, 89520, 89563, 91878, 91931, 173150, 173211, 192948, 193019, 524659, 524738, 865383, 865472, 876639, 876740, 890581, 890688, 904381, 904494, 918985, 919116, 1629115, 1629254, 1647255, 1647406, 1666931, 1667094, 1687929, 1688102
Offset: 1

Views

Author

N. J. A. Sloane, Oct 21 2021

Keywords

Crossrefs

Cf. A307720, A307730, A348246, A348409, A348249, A348252-A348256.

A348460 a(n) = min(A307720(n), A307720(n+1)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3
Offset: 1

Views

Author

N. J. A. Sloane, Oct 30 2021

Keywords

Comments

This is the minimum of A348241 and A348242. It is the lower line (red or blue) in Cheswick's pictures in A348248.
A companion to A348459.

Links

Crossrefs

Cf. A307720, A307730, A348459.

Programs

  • PARI
    See Links section.
Previous Showing 31-33 of 33 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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