A210956 Triangle read by rows: T(n,k) = sum of all parts <= k in the last section of the set of partitions of n.
1, 1, 3, 2, 2, 5, 3, 7, 7, 11, 5, 7, 10, 10, 15, 7, 15, 21, 25, 25, 31, 11, 17, 23, 27, 32, 32, 39, 15, 31, 40, 52, 57, 63, 63, 71, 22, 36, 54, 62, 72, 78, 85, 85, 94, 30, 60, 78, 98, 113, 125, 132, 140, 140, 150, 42, 72, 102, 122, 142, 154, 168, 176, 185, 185, 196
Offset: 1
Examples
Triangle begins: 1; 1, 3; 2, 2, 5; 3, 7, 7, 11; 5, 7, 10, 10, 15; 7, 15, 21, 25, 25, 31; 11, 17, 23, 27, 32, 32, 39; 15, 31, 40, 52, 57, 63, 63, 71; 22, 36, 54, 62, 72, 78, 85, 85, 94;
Links
- Andrew Howroyd, Table of n, a(n) for n = 1..1275
Crossrefs
Programs
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PARI
Row(n)={my(v=vector(n)); v[1]=numbpart(n-1); if(n>1, forpart(p=n, for(k=1, #p, v[p[k]]++), [2,n])); for(k=2, n, v[k]=v[k-1]+k*v[k]); v} { for(n=1, 10, print(Row(n))) }
Formula
T(n,k) = Sum_{j=1..k} A207383(n,j).
Extensions
Terms a(46) and beyond from Andrew Howroyd, Feb 19 2020
Comments