A336876 a(n) is the least m such that A336826(n) = m*p(m) (where p(m) is the product of decimal digits of m).

0, 1, 2, 3, 11, 4, 12, 5, 6, 13, 21, 7, 14, 8, 15, 9, 22, 31, 16, 111, 17, 23, 18, 41, 19, 24, 112, 121, 25, 51, 33, 26, 42, 113, 61, 27, 131, 34, 211, 28, 114, 122, 71, 43, 52, 29, 35, 141, 115, 36, 116, 44, 123, 62, 151, 37, 132, 53, 91, 212, 221, 45, 38

Offset

1,3

Comments

Some terms of A336826 have several representations as the product of a number and of its decimal digits; for example 549504 has four such representations: 1696 * 1 * 6 * 9 * 6, 2862 * 2 * 8 * 6 * 2, 3392 * 3 * 3 * 9 * 2 and 3816 * 3 * 8 * 1 * 6.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Rémy Sigrist, C program for A336876

Formula

A098736(a(n)) = A336826(n).

Example

For n = 26:
- A336826(26) = 192,
- the divisors d of 192, alongside d*p(d), are:
  d    d*p(d)
  ---  ------
    1       1
    2       4
    3       9
    4      16
    6      36
    8      64
   12      24
   16      96
   24     192
   32     192
   48    1536
   64    1536
   96    5184
  192    3456
- so a(26) = min(24, 32) = 24.

Prog

(C) See Links section.

Crossrefs

Cf. A007954, A098736, A336826, A336879.

Sequence in context: A073098 A201267 A046641 * A083664 A083125 A332661

Adjacent sequences: A336873 A336874 A336875 * A336877 A336878 A336879

Keyword

nonn,look,base

Author

Rémy Sigrist, Aug 06 2020

Status

approved