A132135 Number of base-3 "Punctual Birds" with n base-3 digits.
2, 3, 4, 10, 20, 51, 133, 359, 975, 2700, 7506, 20962, 58968, 166170
Offset: 1
Examples
a(2)=3 because 3 of the six 2-digit base-3 numbers appear in their natural order in the string of concatenated base-3 numbers. These 3 numbers are 3, 4 and 6 (10, 11 and 20 base-3).
Crossrefs
Cf. A132134.