A340279 - OEIS

%I #5 Jan 03 2021 15:54:27

%S 0,0,1,1,2,2,4,4,6,6,10,8,14,12,16,16,24,18,30,24,32,30,43,32,49,42,

%T 54,48,68,48,78,64,80,72,93,72,110,90,111,96,134,96,148,120,144,132,

%U 175,128,187,150,189,168,221,162,230,191,236,209,273,192,293,239,285,255

%N Number of partitions of n into 3 parts such that the smallest part is relatively prime to at least one other part.

%H <a href="/index/Par#part">Index entries for sequences related to partitions</a>

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

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

%Y Cf. A340278, A340280.

%K nonn

%O 1,5

%A _Wesley Ivan Hurt_, Jan 02 2021