A340275 Number of partitions of n into 3 parts whose smallest two parts are relatively prime.
0, 0, 1, 1, 2, 2, 3, 4, 5, 5, 7, 8, 10, 11, 12, 13, 16, 17, 20, 22, 24, 25, 29, 30, 33, 35, 38, 40, 45, 47, 52, 55, 58, 60, 64, 66, 72, 75, 79, 81, 88, 90, 97, 101, 105, 108, 116, 119, 126, 130, 135, 139, 148, 151, 157, 161, 167, 171, 181, 183, 193, 198, 204, 209, 217, 221
Offset: 1
Keywords
Programs
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Mathematica
Table[Sum[Sum[Floor[1/GCD[i, k]], {i, k, Floor[(n - k)/2]}], {k, Floor[n/3]}], {n, 100}]
Formula
a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} floor(1/gcd(i,k)).