A340276 Number of partitions of n into 3 parts whose largest two parts are relatively prime.
0, 0, 1, 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
Offset: 1
Keywords
Programs
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Mathematica
Table[Sum[Sum[Floor[1/GCD[i, n - i - k]], {i, k, Floor[(n - k)/2]}], {k, Floor[n/3]}], {n, 80}]
Formula
a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} floor(1/gcd(i,n-i-k)).