A085890 7-smooth numbers (A002473) using digits in descending order. Zero is followed by a 9.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 32, 54, 98, 210, 432

Offset: 1

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jul 10 2003

Keywords

• base
• nonn

Comments

No more terms < 10^1000. Probably no more terms. - David Wasserman, Feb 10 2005

Examples

			432 is a member as 432= 2^4*3^3.
		

Crossrefs

Intersection of A002473 and A158699.

Cf. A085889.

Programs

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

More terms from David Wasserman, Feb 10 2005