Triangle of coefficients of Legendre polynomials 2^n P_n (x).

Terms

a(0) =1a(1) =2a(2) =6a(3) =2a(4) =20a(5) =12a(6) =70a(7) =60a(8) =6a(9) =252a(10) =280a(11) =60a(12) =924a(13) =1260a(14) =420a(15) =20a(16) =3432a(17) =5544a(18) =2520a(19) =280a(20) =12870a(21) =24024a(22) =13860a(23) =2520a(24) =70a(25) =48620a(26) =102960a(27) =72072a(28) =18480a(29) =1260