OFFSET
1,2
COMMENTS
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..12946 (rows n = 1..5000, flattened)
Michael De Vlieger, Fast Mathematica programs that construct A008479, A010846, A162306, and A369609
FORMULA
EXAMPLE
First rows of the triangle:
1;
2;
3;
2, 4;
5;
6;
7;
2, 4, 8;
3, 9;
10;
11;
6, 12;
13;
14;
15;
2, 4, 8, 16;
17;
6, 12, 18;
etc.
MATHEMATICA
f[x_] := f[x] = Times @@ FactorInteger[x][[All, 1]]; Flatten@ Table[r = f[n]; Select[Range[n], f[#] == r &], {n, 44}]
PROG
(PARI) rad(n) = factorback(factorint(n)[, 1]); \\ A007947
row(n) = my(r=rad(n)); select(x->(rad(x) == r), [1..n]); \\ Michel Marcus, May 11 2024
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Michael De Vlieger, May 09 2024
STATUS
approved