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”).

A241733
Number of partitions p of n such that round(mean(p)) is a part of p; here, round(x) means floor(x + 1/2).
3
0, 1, 2, 3, 4, 5, 7, 10, 13, 18, 24, 31, 44, 57, 73, 94, 127, 166, 203, 268, 338, 424, 548, 674, 858, 1046, 1321, 1643, 1973, 2472, 3026, 3774, 4529, 5455, 6736, 8013, 9699, 11899, 14299, 16926, 20377, 24373, 29018, 34679, 41447, 48688, 57395, 68775, 81535
OFFSET
0,3
COMMENTS
For the corresponding sequence using "round" as in Mathematica, see A241338.
FORMULA
a(n) + A241734(n) = A000041(n) for n >= 0.
EXAMPLE
a(6) counts these 7 partitions: 6, 33, 321, 222, 2211, 21111, 111111.
MATHEMATICA
z = 40; f[n_] := f[n] = IntegerPartitions[n];
Table[Count[f[n], p_ /; MemberQ[p, Floor[Mean[p] + 1/2]]], {n, 0, z}] (* A241733 *)
Table[Count[f[n], p_ /; ! MemberQ[p, Floor[Mean[p] + 1/2]]], {n, 0, z}] (* A241734 *)
CROSSREFS
Sequence in context: A193771 A160333 A174578 * A241338 A271489 A018127
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Apr 28 2014
STATUS
approved