a(n) = 7*a(n-1) - 23*a(n-2) + 49*a(n-3) - 49*a(n-4) with a(0)=0, a(1)=1, a(2)=7, a(3)=19.

Terms

a(0) =0a(1) =1a(2) =7a(3) =19a(4) =21a(5) =4a(6) =133a(7) =937a(8) =2667a(9) =3439a(10) =2128a(11) =20569a(12) =132867a(13) =392743a(14) =596869a(15) =647596a(16) =3539109a(17) =19881229a(18) =60254719a(19) =106198903a(20) =158297664a(21) =643809889a(22) =3117087967a(23) =9564827611a(24) =19050869061a(25) =34555674196a(26) =119658973525a(27) =507648339217