Number of set partitions of [4n] into 4-element subsets {i, i+k, i+2k, i+3k} with 1<=k<=n.
A337520
Number of set partitions of [4n] into 4-element subsets {i, i+k, i+2k, i+3k} with 1<=k<=n.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =22a(6) =64a(7) =147a(8) =409a(9) =1092a(10) =3253a(11) =8661a(12) =28585a(13) =83190a(14) =274001a(15) =912373a(16) =3366384a(17) =13253582a(18) =61533277a(19) =290493694
External references
- oeis: A337520