

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
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OFFSET

1,2


COMMENTS

a(n) = least positive integer > a(n1) and not equal to a(i)+a(j)a(k) for distinct i and j with 1 <= i,j,k <= n1. [Comment corrected by JeanPaul Delahaye, Oct 02 2020.]


LINKS



FORMULA



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)


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



