Number of Sidon subsets of {1,...,n} of size 4.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =2a(7) =10a(8) =26a(9) =60a(10) =110a(11) =190a(12) =304a(13) =466a(14) =676a(15) =958a(16) =1312a(17) =1762a(18) =2310a(19) =2984a(20) =3786a(21) =4750a(22) =5874a(23) =7196a(24) =8720a(25) =10484a(26) =12488a(27) =14780a(28) =17360a(29) =20276