OFFSET
1,2
FORMULA
a(n) = Sum_{k=1..n} mu(1+n*(k-1))^2, where mu is the Möbius function.
EXAMPLE
[1 2 3 4 5]
[1 2 3 4] [6 7 8 9 10]
[1 2 3] [5 6 7 8] [11 12 13 14 15]
[1 2] [4 5 6] [9 10 11 12] [16 17 18 19 20]
[1] [3 4] [7 8 9] [13 14 15 16] [21 22 23 24 25]
------------------------------------------------------------------------
n 1 2 3 4 5
------------------------------------------------------------------------
a(n) 1 2 2 3 4
------------------------------------------------------------------------
numbers {1} {1,3} {1,7} {1,5,13} {1,6,11,21}
------------------------------------------------------------------------
MATHEMATICA
Table[Sum[MoebiusMu[1 + n (k - 1)]^2, {k, n}], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, May 17 2021
STATUS
approved