login
A104857
Positive integers that cannot be represented as the sum of distinct Lucas 3-step numbers (A001644).
0
2, 5, 6, 9, 13, 16, 17, 20, 23, 26, 27, 30, 34, 37, 38, 41, 44, 45, 48, 52, 55, 56, 59, 62, 65, 66, 69, 73, 76, 77, 80, 84, 87, 88, 91, 94, 97, 98, 101, 105, 108, 109, 112, 115, 116, 119, 123, 126, 127, 130, 133, 136, 137, 140, 144, 147, 148, 151, 154
OFFSET
1,1
COMMENTS
Similar to A054770 "Numbers that are not the sum of distinct Lucas numbers (A000204)" but with Lucas 3-step numbers (A001644). Wanted: equivalent of David W. Wilson conjecture (A054770) as proved by Ian Agol. Note that all positive integers can be presented as the sum of distinct Fibonacci numbers in A000119 way. Catalani called Lucas 3-step numbers "generalized Lucas numbers" but that is quite ambiguous. These are also called tribonacci-Lucas numbers.
LINKS
Eric Weisstein's World of Mathematics, Lucas n-Step Number.
EXAMPLE
In "base Lucas 3-step numbers" we can represent 1 as "1", but cannot represent 2 because there is no next Lucas 3-step number until 3 and we can't have two instances of 1 summed here. We can represent 3 as "10" (one 3 and no 1's), 4 as "11" (one 3 and one 1). Then we cannot represent 5 or 6 because there is no next Lucas 3-step number until 7 and we can't sum two 3s or six 1's. 7 becomes "100" (one 7, no 3s and no 1's), 8 becomes "101" and so forth.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Apr 24 2005
EXTENSIONS
More terms from T. D. Noe, Apr 26 2005
STATUS
approved