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A011185 A B_2 sequence: a(n) = least value such that sequence increases and pairwise sums of distinct elements are all distinct. 17
1, 2, 3, 5, 8, 13, 21, 30, 39, 53, 74, 95, 128, 152, 182, 212, 258, 316, 374, 413, 476, 531, 546, 608, 717, 798, 862, 965, 1060, 1161, 1307, 1386, 1435, 1556, 1722, 1834, 1934, 2058, 2261, 2497, 2699, 2874, 3061, 3197, 3332, 3629, 3712, 3868, 4140, 4447, 4640 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
a(n) = least positive integer > a(n-1) and not equal to a(i)+a(j)-a(k) for distinct i and j with 1 <= i,j,k <= n-1. [Comment corrected by Jean-Paul Delahaye, Oct 02 2020.]
LINKS
Klaus Brockhaus and Dan Hoey, Table of n, a(n) for n = 1..2839
FORMULA
a(n) = A010672(n-1)+1.
PROG
(Python)
from itertools import islice
def agen(): # generator of terms
aset, sset, k = set(), set(), 0
while True:
k += 1
while any(k+an in sset for an in aset): k += 1
yield k; sset.update(k+an for an in aset); aset.add(k)
print(list(islice(agen(), 51))) # Michael S. Branicky, Feb 05 2023
CROSSREFS
Cf. A010672.
Sequence in context: A080787 A065124 A048817 * A240733 A283936 A278800
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified May 19 14:45 EDT 2024. Contains 372698 sequences. (Running on oeis4.)