C(n + 1, 2) + n - 1.
1, 4, 8, 13, 19, 26, 34, 43, 53, 64, 76, 89, 103, 118, 134, 151, 169, 188, 208, 229, 251
1 seqfan posts
Sun Jun 6 10:45:59 CEST 2010 [seqfan] Re: A048200 variant: invert [1, 2, ..., n] allowing one swap and two shift-rotate operations