|
| |
|
|
A176385
|
|
The smallest number which when multiplied by the n-th repunit gives a Smith number.
|
|
1
|
|
|
|
4, 2, 6, 56, 32, 97, 6, 95, 176, 4, 32, 309, 68, 68, 194, 616, 175, 96, 1540, 4, 816, 14, 1540, 95, 840, 32, 5, 437, 50, 10336, 95, 5, 995, 976, 175, 14, 40, 570, 1976, 995, 1400, 294, 1994, 176, 544, 507, 328, 392, 77, 11020, 18905, 18050, 9995, 779, 4, 805, 669
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
Smith numbers, A006753: the digits-sum equals the digits-sum of its prime factors.
Repunits: R(n)=(10^n-1)/9 = A002275(n).
|
|
|
LINKS
|
Paul Weisenhorn, Table of n, a(n) for n = 1..70
|
|
|
EXAMPLE
|
R(3)=111 multiplied by a(3)=6 yields z=666=2*3*3*37 = A006753(34): 6+6+6 = 2+3+3+3+7 = 18.
|
|
|
MAPLE
|
# digits-sum of primfactors of z=dsp(z)
for n from 2 to 70 do f(n):=1: test:=false:
while (f(n) < 420000) and (test=false) do
f(n):=f(n)+1: z:=f(n)*r(n): ds(z):=0:
dsp(z):=dsp(r(n))+dsp(f(n)):
while (z>0) do z:=iquo(z, 10, 'm'): ds(z):=ds(z)+m: end do:
if(ds(z)=dsp(z)) then test:=true: print(n, f(n)): end if:
end do: end do:
|
|
|
CROSSREFS
|
Sequence in context: A019105 A183399 A248250 * A155829 A181051 A299631
Adjacent sequences: A176382 A176383 A176384 * A176386 A176387 A176388
|
|
|
KEYWORD
|
nonn,base
|
|
|
AUTHOR
|
Paul Weisenhorn, Apr 16 2010, Apr 23 2010
|
|
|
EXTENSIONS
|
Keyword:base added by R. J. Mathar, Apr 24 2010
|
|
|
STATUS
|
approved
|
| |
|
|
