cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A326687 Sum of the second largest parts in the partitions of n into 10 primes.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 3, 5, 6, 8, 14, 14, 19, 26, 34, 38, 49, 53, 70, 81, 96, 105, 139, 140, 187, 204, 246, 263, 326, 341, 437, 452, 543, 562, 715, 700, 898, 904, 1100, 1101, 1387, 1343, 1720, 1643, 2037, 1982
Offset: 0

Views

Author

Wesley Ivan Hurt, Jul 17 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Total[Select[IntegerPartitions[n,{10}],AllTrue[#,PrimeQ]&][[All,2]]],{n,0,70}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Apr 04 2021 *)

Formula

a(n) = Sum_{r=1..floor(n/10)} Sum_{q=r..floor((n-r)/9)} Sum_{p=q..floor((n-q-r)/8)} Sum_{o=p..floor((n-p-q-r)/7)} Sum_{m=o..floor((n-o-p-q-r)/6)} Sum_{l=m..floor((n-m-o-p-q-r)/5)} Sum_{k=l..floor((n-l-m-o-p-q-r)/4)} Sum_{j=k..floor((n-k-l-m-o-p-q-r)/3)} Sum_{i=j..floor((n-j-k-l-m-o-p-q-r)/2)} c(r) * c(q) * c(p) * c(o) * c(m) * c(l) * c(k) * c(j) * c(i) * c(n-i-j-k-l-m-o-p-q-r) * i, where c is the prime characteristic (A010051).
a(n) = A326678(n) - A326679(n) - A326680(n) - A326681(n) - A326682(n) - A326683(n) - A326684(n) - A326685(n) - A326686(n) - A326688(n).