|
| |
|
|
A085908
|
|
Smallest 7-smooth number beginning with n.
|
|
0
|
|
|
|
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 112, 12, 135, 14, 15, 16, 175, 18, 192, 20, 21, 224, 2304, 24, 25, 2625, 27, 28, 294, 30, 315, 32, 336, 343, 35, 36, 375, 384, 392, 40, 4116, 42, 432, 441, 45, 4608, 4704, 48, 49, 50, 512, 525, 5376, 54, 55125, 56, 576, 588, 59049, 60
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,2
|
|
|
LINKS
|
Table of n, a(n) for n=0..59.
|
|
|
EXAMPLE
|
a(23) = 2304 = 2^8*3^2 is the smallest 7-smooth number beginning with 23. (23, 230, 231, 232, ..., 239, 2301, 2302, 2303 etc. have a divisor > 10.)
|
|
|
MATHEMATICA
|
a[n_] := Module[{d = IntegerDigits[n], k = 1}, While[Max[FactorInteger[k][[;; , 1]]] > 7 || Length[IntegerDigits[k]] < Length[d] || IntegerDigits[k][[1 ;; Length[d]]] != d, k++]; k]; Array[a, 60] (* Amiram Eldar, Apr 30 2022 *)
|
|
|
PROG
|
(PARI) hc(n) = local(f); f = factor(n); f[matsize(f)[1], 1] < 10;
a(n) = local(d, x); if (hc(n), return(n)); d = 1; while (d, for (i = 1, 10^d - 1, x = n*10^d + i; if (hc(x), return(x))); d++); \\ David Wasserman, Feb 11 2005
|
|
|
CROSSREFS
|
Cf. A002473.
Sequence in context: A258373 A250266 A357936 * A110304 A043315 A044912
Adjacent sequences: A085905 A085906 A085907 * A085909 A085910 A085911
|
|
|
KEYWORD
|
base,nonn
|
|
|
AUTHOR
|
Amarnath Murthy, Jul 09 2003
|
|
|
EXTENSIONS
|
Corrected and extended by David Wasserman, Feb 11 2005
Name corrected by J. Lowell, Apr 30 2022
|
|
|
STATUS
|
approved
|
| |
|
|
