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A073911
Smallest number m such that m and the product of digits of m are both divisible by 5n, or 0 if no such number exists.
4
5, 0, 135, 0, 525, 0, 175, 0, 495, 0, 0, 0, 0, 0, 3525, 0, 0, 0, 0, 0, 735, 0, 0, 0, 55125, 0, 3915, 0, 0, 0, 0, 0, 0, 0, 1575, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15975, 0, 0, 0, 37975, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9765, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 155625, 0, 0, 0, 0, 0, 31995, 0, 0
OFFSET
1,1
COMMENTS
Here 0 is regarded as not divisible by any number.
a(n) = 0 if n is divisible by 2 or contains a prime divisor > 9. - Sascha Kurz, Aug 23 2002
FORMULA
a(n) = A085124(5*n). - R. J. Mathar, Jun 21 2018
MAPLE
f := 5:for i from 1 to 400 do b := ifactors(f*i)[2]: if b[nops(b)][1]>9 or (f*i mod 10) =0 then a[i] := 0:else j := 0:while true do j := j+f*i:c := convert(j, base, 10): d := product(c[k], k=1..nops(c)): if (d mod f*i)=0 and d>0 then a[i] := j:break:fi: od:fi:od:seq(a[k], k=1..400);
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Amarnath Murthy, Aug 18 2002
EXTENSIONS
More terms from Sascha Kurz, Aug 23 2002
STATUS
approved