OFFSET
1,2
COMMENTS
Numbers m | 42^e with integer e >= 0. - Michael De Vlieger, Aug 22 2019
Sum_{n>=1} 1/a(n) = (2*3*7)/((2-1)*(3-1)*(7-1)) = 7/2. - Amiram Eldar, Sep 24 2020
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
FORMULA
a(n) ~ exp((6*log(2)*log(3)*log(7)*n)^(1/3)) / sqrt(42). - Vaclav Kotesovec, Sep 23 2020
MATHEMATICA
With[{n = 567}, Sort@ Flatten@ Table[2^i * 3^j * 7^k, {i, 0, Log2@ n}, {j, 0, Log[3, n/2^i]}, {k, 0, Log[7, n/(2^i*3^j)]}]] (* Michael De Vlieger, Aug 22 2019 *)
PROG
(PARI) list(lim)=my(v=List(), s, t); for(i=0, logint(lim\=1, 7), t=7^i; for(j=0, logint(lim\t, 3), s=t*3^j; while(s<=lim, listput(v, s); s<<=1))); Set(v) \\ Charles R Greathouse IV, Nov 20 2024
CROSSREFS
KEYWORD
nonn,easy,changed
AUTHOR
Douglas Winston (douglas.winston(AT)srupc.com), Jun 30 2005
STATUS
approved