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

1,6

Links

Table of n, a(n) for n=1..66.

Index entries for sequences related to partitions

Formula

a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} floor(1/gcd(i,n-i-k)).

Mathematica

Table[Sum[Sum[Floor[1/GCD[i, n - i - k]], {i, k, Floor[(n - k)/2]}], {k, Floor[n/3]}], {n, 80}]

Crossrefs

Cf. A023023, A340275, A340278.

Sequence in context: A165684 A342519 A307780 * A340275 A348323 A367214

Adjacent sequences: A340273 A340274 A340275 * A340277 A340278 A340279

Keyword

nonn

Author

Wesley Ivan Hurt, Jan 02 2021

Status

approved