Single paradiddlde. In percussion, the paradiddle is a four-note drum sticking pattern consisting of two alternating notes followed by two notes on the same hand.
a(n)=(1/56)*{8*(n mod 8)+[(n+1) mod 8]-6*[(n+2) mod 8]+8*[(n+3) mod 8]-6*[(n+4) mod 8]+[(n+5) mod 8]+8*[(n+6) mod 8]-6*[(n+7) mod 8]}, with n>=0. - Paolo P. Lava (ppl(AT)spl.at), Nov 09 2007