A064970 a(1)=1; thereafter, values of n for which r(n)-r(n-1) and r(n-1)-r(n-2) have the same sign, where r(n) = A005132(n).

1, 2, 3, 6, 7, 18, 19, 23, 33, 34, 38, 66, 67, 77, 101, 102, 110, 111, 113, 114, 115, 119, 120, 129, 133, 134, 136, 172, 173, 185, 189, 190, 192, 193, 196, 224, 225, 235, 287, 288, 306, 307, 339, 340, 352, 367, 405, 406, 420, 452, 453, 465, 466

Offset: 1

Author

Allan Wilks, Oct 30 2001

Keywords

• nonn

Examples

			E.g., going from r(4)=2 to r(5)=7 to r(6)=13 we increase twice in a row, so 6 is a member. Going from r(21)=63 to r(22)=41 to r(23)=18 we decrease twice in a row, so 23 is a member.
		

Links

• Index entries for sequences related to Recamán's sequence

Crossrefs

Cf. A005132.

Extensions

Better description from Dean Hickerson, Feb 15 2006