OFFSET
1,2
EXAMPLE
The prime factors of 108 are (2,2,3,3,3), with odd bisection (2,3,3), with product 18, so a(108) = 18.
The prime factors of 720 are (2,2,2,2,3,3,5), with odd bisection (2,2,3,5), with product 60, so a(720) = 60.
MATHEMATICA
Table[Times@@First/@Partition[Append[Flatten[Apply[ConstantArray, FactorInteger[n], {1}]], 0], 2], {n, 100}]
CROSSREFS
Positions of 2's are A001747.
The even reverse version appears to be A329888.
Positions of first appearances are A342768.
The reverse version is A346701.
The even version is A346704.
A001221 counts distinct prime factors.
A001222 counts all prime factors.
A209281 (shifted) adds up the odd bisection of standard compositions.
A344606 counts alternating permutations of prime indices.
A344617 gives the sign of the alternating sum of prime indices.
A346633 adds up the even bisection of standard compositions.
A346698 gives the sum of the even bisection of prime indices.
A346700 gives the sum of the even bisection of reversed prime indices.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Aug 08 2021
STATUS
approved