login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

a(n) = 2*nextprime(n - 1) - 2*n, where nextprime(n) is the smallest prime > n.
0

%I #8 May 11 2019 02:22:18

%S 2,0,0,2,0,2,0,6,4,2,0,2,0,6,4,2,0,2,0,6,4,2,0,10,8,6,4,2,0,2,0,10,8,

%T 6,4,2,0,6,4,2,0,2,0,6,4,2,0,10,8,6,4,2,0,10,8,6,4,2,0,2,0,10,8,6,4,2,

%U 0,6,4,2,0,2,0,10,8,6,4,2,0,6,4,2,0,10

%N a(n) = 2*nextprime(n - 1) - 2*n, where nextprime(n) is the smallest prime > n.

%C For n > 1, a(n) is the difference of the larger and smaller part of the single partition of 2n into two parts whose larger part is the smallest prime > n - 1.

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

%F a(n) = 2*A151800(n - 1) - 2*n.

%e a(9) = 4; the smallest prime > 8 is 11, 2*9-11 = 7 and 11-7 = 4.

%t Table[2 NextPrime[n - 1, 1] - 2 n, {n, 100}]

%Y Cf. A151800.

%K nonn

%O 1,1

%A _Wesley Ivan Hurt_, May 10 2019