A215649 Reversals of tribonacci numbers (sorted).

0, 0, 1, 1, 2, 4, 7, 18, 31, 42, 44, 405, 472, 729, 941, 5071, 6313, 8675, 9853, 21066, 31591, 90601, 447014, 514121, 674557, 713322, 770074, 4606468, 7359831, 7575552, 8089735, 19520951, 52494292, 69005989, 106799181, 474396516, 777547433, 2586342311, 3016782802

Offset: 0

Author

Jonathan Vos Post, Mar 09 2013

Keywords

• nonn
• base
• easy

Comments

This is to A004170 as tribonacci numbers A000073 are to Fibonacci numbers A000045. Note that tribonacci(20) = 35890 is, upon reversal, 09853, then the leading 0 is truncated, making the 5-digit number into the 4-digit number 9853. Similarly, R(4700770) = 770074.

Examples

			A000073(n) for n = 7, 8, 9 = 13, 24, 44, 81. Reversed, those are 31, 42, 44, 18, and sorted that is 18, 31, 42, 44.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A000045, A000073, A004086, A004170, A004091, A140463, A214855, A004086.

Programs

Mathematica

Sort[FromDigits[Reverse[IntegerDigits[#]]]&/@LinearRecurrence[{1,1,1},{0,0,1,1},40]] (* Harvey P. Dale, Nov 22 2015 *)