a(1) = 5; a(n) is the sum of |a(m) - m| for m < n.

Terms

a(0) =5a(1) =4a(2) =6a(3) =9a(4) =14a(5) =23a(6) =40a(7) =73a(8) =138a(9) =267a(10) =524a(11) =1037a(12) =2062a(13) =4111a(14) =8208a(15) =16401a(16) =32786a(17) =65555a(18) =131092a(19) =262165a(20) =524310a(21) =1048599a(22) =2097176a(23) =4194329a(24) =8388634a(25) =16777243a(26) =33554460a(27) =67108893a(28) =134217758a(29) =268435487