Fill an infinite square array by following a spiral around the origin; in the central cell enter a(0)=1; thereafter, in the n-th cell, enter the sum of the entries of those earlier cells that can be seen from that cell.
A280027
Fill an infinite square array by following a spiral around the origin; in the central cell enter a(0)=1; thereafter, in the n-th cell, enter the sum of the entries of those earlier cells that can be seen from that cell.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =4a(4) =7a(5) =13a(6) =23a(7) =42a(8) =76a(9) =146a(10) =239a(11) =441a(12) =852a(13) =1389a(14) =2536a(15) =4971a(16) =9832a(17) =15312a(18) =27964a(19) =54801a(20) =108787a(21) =169086a(22) =308758a(23) =603612a(24) =1201837a(25) =2397202a(26) =3656904a(27) =6687912a(28) =13067709a(29) =25998877
External references
- oeis: A280027