Number of nondecreasing arrays of n 1..n integers with the sum of their 2nd powers equal to sum(i^2,i=1..n).
A216640
Number of nondecreasing arrays of n 1..n integers with the sum of their 2nd powers equal to sum(i^2,i=1..n).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =3a(6) =8a(7) =25a(8) =83a(9) =257a(10) =788a(11) =2491a(12) =7885a(13) =25099a(14) =80481a(15) =264505a(16) =884517a(17) =2994535a(18) =10208806a(19) =35095825a(20) =121699761a(21) =424273761a(22) =1487693075a(23) =5244197347a(24) =18584820912a(25) =66169376686a(26) =236592018517a(27) =849466213882
External references
- oeis: A216640