A055562 a(n) = least number greater than a(n-1) not the sum of an earlier pair of consecutive terms, a(0) = 2.

2, 3, 4, 6, 8, 9, 11, 12, 13, 15, 16, 18, 19, 21, 22, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44, 45, 47, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 64, 66, 67, 69, 70, 72, 73, 75, 76, 78, 79, 81, 82, 84, 85, 87, 88, 90, 91, 93, 94, 96, 98, 99, 101, 102, 104, 105

Offset: 0

Author

Henry Bottomley, May 26 2000

Keywords

• nonn

Examples

			a(2) = 4 because a(1) = 3 and 4 <> a(0)+a(1);
a(3) = 6 because a(2) = 4 and 5 = a(0)+a(1) but 6 <> a(0)+a(1) and 6 <> a(1)+a(2).
		

Links

• Ivan Neretin, Table of n, a(n) for n = 0..10000
• J.-P. Allouche and J. Shallit, The Ring of k-regular Sequences, II
• J.-P. Allouche and J. Shallit, The ring of k-regular sequences, II, Theoret. Computer Sci., 307 (2003), 3-29.

Crossrefs

Complement of A022441. See A001651 for a(0) = 1 and A055563 for a(0) = 3

Formula

a(n) = A022441(n) - a(n-1) for n > 0.

a(2n) = 3n + 1 + (floor(log_2 n) mod 2), n >= 1; a(2n+1) = 3n+3, n >= 0. - Jeffrey Shallit, Jun 08 2000

a(n) = A210770(2*n+2). - Reinhard Zumkeller, Mar 25 2012