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A305231 Numbers that are the product of some integer and its digit reversal. 3
0, 1, 4, 9, 10, 16, 25, 36, 40, 49, 64, 81, 90, 100, 121, 160, 250, 252, 360, 400, 403, 484, 490, 574, 640, 736, 765, 810, 900, 976, 1000, 1008, 1089, 1207, 1210, 1300, 1458, 1462, 1600, 1612, 1729, 1855, 1936, 1944, 2268, 2296, 2430, 2500, 2520, 2668, 2701 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Terms of A061205, sorted in increasing order, with duplicates removed.

LINKS

Jon E. Schoenfield, Table of n, a(n) for n = 1..10000 (first 1000 terms from Alois P. Heinz)

EXAMPLE

12*21 = 252, so 252 is a term.

156*651 = 101556, so 101556 is a term. (It can also be written as 273*372; see A203924.)

MAPLE

a:= proc(n) option remember; local k, d; for k from 1+a(n-1) do

      for d in numtheory[divisors](k) do if k = d*(s-> parse(cat(

      seq(s[-i], i=1..length(s)))))(""||d) then return k fi od od

    end: a(1):=0:

seq(a(n), n=1..60);  # Alois P. Heinz, May 27 2018

PROG

(PARI) isok(n) = if (n==0, return (1), fordiv(n, d, if (n/d == fromdigits(Vecrev(digits(d))), return (1))); return (0)); \\ Michel Marcus, May 28 2018

CROSSREFS

Cf. A061205, A203924.

Sequence in context: A337816 A272266 A155566 * A312832 A236652 A236748

Adjacent sequences:  A305228 A305229 A305230 * A305232 A305233 A305234

KEYWORD

nonn,base

AUTHOR

Jon E. Schoenfield, May 27 2018

STATUS

approved

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Last modified November 27 10:45 EST 2021. Contains 349366 sequences. (Running on oeis4.)