A138607 List first A008578(1) odd numbers, then first A008578(2) even numbers, then the next A008578(3) odd numbers, then the next A008578(4) even numbers, etc.
1, 2, 4, 3, 5, 7, 6, 8, 10, 12, 14, 9, 11, 13, 15, 17, 19, 21, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73
Offset: 1
Examples
Let S1={1} S2={2,4} S3={3,5,7} S4={6,8,10,12,14} S5={9,11,13,15,17,19,21} S6={16,18,20,22,24,26,28,30,32,34,36} ... then S1, S2, S3, S4, S5, S6,... gives this sequence.
Formula
If n < 3, a(n) = n. If n-2 = A007504(A083375(n-2)), then a(n) = a(n-1-A000040(A083375(n-2)))+2, otherwise a(n) = a(n-1)+2. - Antti Karttunen, Oct 05 2009.
Extensions
Edited, extended, and offset changed from 0 to 1 by Antti Karttunen, Oct 05 2009
Comments