Triangle read by rows: every third term of every third row of A008292.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2416a(5) =1a(6) =1a(7) =455192a(8) =455192a(9) =1a(10) =1a(11) =45533450a(12) =2275172004a(13) =45533450a(14) =1a(15) =1a(16) =3572085255a(19) =3572085255a(20) =1a(21) =1a(22) =251732291184a(26) =251732291184a(27) =1a(28) =1