OFFSET
1,4
COMMENTS
For n >= 3, a(n) is the difference of n and the smallest prime appearing among the larger parts of the partitions of n into two parts.
FORMULA
a(n) = n - A151800(ceiling(n/2) - 1).
EXAMPLE
a(7) = 2; n = 7 has three partitions into two parts: (6,1), (5,2) and (4,3). The smallest prime among the larger parts is 5 and 7 - 5 = 2.
MATHEMATICA
Table[n - NextPrime[Ceiling[n/2] - 1, 1], {n, 100}]
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Wesley Ivan Hurt, May 10 2019
STATUS
approved