a(n) = (1/5)*A290909(n), n>= 0.

Terms

a(0) =0a(1) =1a(2) =4a(3) =15a(4) =60a(5) =240a(6) =956a(7) =3809a(8) =15180a(9) =60495a(10) =241080a(11) =960736a(12) =3828664a(13) =15257745a(14) =60804180a(15) =242312895a(16) =965649716a(17) =3848244944a(18) =15335777460a(19) =61115150865a(20) =243552156060a(21) =970588338271