OFFSET
1,4
EXAMPLE
a(6) counts these partitions:
51 (as part (5+1)/2 = 3 is not included),
42 (as (4+2)/2 = 3 is not included),
411 (as (4+1)/2 = 2.5 cannot be included),
3111 (as (3+1)/2 = 2 is not included),
2211 (as (2+1)/2 = 1.5 cannot be included),
21111 (ditto).
Thus a(6) = 6.
MATHEMATICA
Table[Count[IntegerPartitions[n], p_ /; !MemberQ[p, (Min[p] + Max[p])/2]], {n, 40}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Feb 27 2014
STATUS
approved