A229544 Numbers n such that n*product_of_digits(n) is a nonzero cube.

1, 8, 243, 784, 7776, 9826, 13122, 24389, 26244, 39366, 47628, 55566, 59895, 71442, 82944, 122825, 124416, 226981, 263424, 275625, 316368, 323433, 333396, 588245, 663255, 774144, 843648, 1339893, 1492992, 1613472, 2341344, 3816336, 3981312, 8719893, 8992364, 9393931, 9927988, 11212884, 11239424, 14823774

Offset

1,2

Links

Table of n, a(n) for n=1..40.

Example

7776*(7*7*7*6) = 1600030008 = 252^3. Thus, 7776 is a member of this sequence.

Prog

(Python)
def DP(n):
..p = 1
..for i in str(n):
....p *= int(i)
..return p
def a(n):
..k = 0
..while k < n:
....if k**3 == n*DP(n):
......return n
....if k**3 > n*DP(n):
......return 0
....k += 1
n = 1
while n < 10**6:
..if a(n):
....print(n, end=', ')
..n += 1
# Simplified by Derek Orr, Mar 22 2015
(PARI) for(n=1, 10^7, d=digits(n); p=prod(i=1, #d, d[i]); if(p&&ispower(n*p, 3), print1(n, ", "))) \\ Derek Orr, Mar 22 2015

Crossrefs

Cf. A066565, A098736.

Sequence in context: A272236 A272239 A227319 * A115613 A209540 A085524

Adjacent sequences: A229541 A229542 A229543 * A229545 A229546 A229547

Keyword

nonn,base

Author

Derek Orr, Sep 25 2013

Extensions

Corrected and extended by Derek Orr, Mar 22 2015

Status

approved