A085889 7-smooth numbers (A002473) using digits in increasing order. 9 is followed by a zero.
1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 45, 56, 90, 567, 3456
Offset: 1
Examples
567 is a member as 567 = 3^4*7.
Programs
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PARI
hcn(n) = while (!(n%2), n \=2); while (!(n%3), n \=3); while (!(n%5), n \=5); while (!(n%7), n \=7); n == 1; for (i = 0, 1000, for (j = 1, 9, my(n = sum(k = j, i + j, (k%10)*10^(i + j - k))); if (hcn(n), print1(n, ", ")))); /* David Wasserman, Feb 10 2005 */
Extensions
3456 from David Wasserman, Feb 10 2005
Comments