OFFSET
1,1
COMMENTS
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
EXAMPLE
a(1) = 40 = 2^3 * 5, since 3 < 4 < 5 and 4 != 2.
a(2) = 56 = 2^3 * 7, since 3 < 4 < 7 and 4 != 2.
a(7) = 176 = 2^4 * 11, since 3 < 8 < 11 and 8 != 2.
a(15) = 297 = 3^3 * 11, since 2 < 9 < 11 and 9 != 3.
a(248) = 3625 = 5^3 * 29, since 2 < 25 < 29 and 25 != 5, etc.
MATHEMATICA
s = Select[Range[1000], Nor[PrimePowerQ[#], SquareFreeQ[#]] &];
Select[s,
And[#3 < #1 < #2, #1 != #4] & @@
{#1/(Times @@ #2), #2[[2]], #3, First[#2]} & @@
{#, FactorInteger[#][[All, 1]],
If[OddQ[#], 2, q = 3; While[Divisible[#, q], q = NextPrime[q]]; q]} &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael De Vlieger, Jan 20 2024
STATUS
approved