Square spiral of sums of selected preceding terms, starting at 1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =5a(5) =10a(6) =11a(7) =23a(8) =25a(9) =26a(10) =54a(11) =57a(12) =59a(13) =122a(14) =133a(15) =142a(16) =147a(17) =304a(18) =330a(19) =351a(20) =362a(21) =747a(22) =806a(23) =880a(24) =931a(25) =957a(26) =1968a(27) =2105a(28) =2275a(29) =2391