A232228 a(1)=1; thereafter a(n) = 2^(number of bits in binary expansion of a(n-1)) + 1 + a(n-1).

1, 4, 13, 30, 63, 128, 385, 898, 1923, 3972, 8069, 16262, 32647, 65416, 130953, 262026, 524171, 1048460, 2097037, 4194190, 8388495, 16777104, 33554321, 67108754, 134217619, 268435348, 536870805, 1073741718, 2147483543, 4294967192, 8589934489, 17179869082, 34359738267, 68719476636

Offset: 1

Author

N. J. A. Sloane, Nov 22 2013

Keywords

• nonn

Comments

An infinite subsequence of A010061.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1001
• D. W. Bange, Solution to Problem E 2408, Amer. Math. Monthly, 81 (1974), 407.
• Index entries for Colombian or self numbers and related sequences

Crossrefs

Cf. A010061.

Programs

Maple

f:=proc(n) option remember; if n=1 then 1 else 2^(nops(convert(f(n-1),base,2)))+1+f(n-1); fi; end;
[seq(f(n),n=1..40)];

Mathematica

NestList[2^IntegerLength[#,2]+1+#&,1,40] (* Harvey P. Dale, May 05 2020 *)