OFFSET
1,1
COMMENTS
Here 0 is regarded as not divisible by any number.
a(n) = 0 if n is divisible by 10 or contains a prime divisor > 9. - Sascha Kurz, Aug 23 2002
FORMULA
a(n) = A085124(7*n). - R. J. Mathar, Jun 21 2018
EXAMPLE
a(8) = 728 is divisible by 7*8 = 56 and also 7*2*8 = 112 = 2*56.
MAPLE
f := 7: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