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A133744
a(n) = A062295(n) - A133743(n).
4
0, 0, 0, 0, 0, 0, 15, -19, -44, 0, 31, 33, 80, 43, 92, 0, 112, 305, 140, -77, 336, 261, 0, -103, -228, 129, 131, 268, 429, 292, -153, -805, -352, 189, 985, 2040, 1260, 440, -693, -468, 239, -2367, -1365, -285, 885, 596, 3531, 2608, 3360, 2752, -2196, 0, 2709, 4367, 4411, 2105
OFFSET
1,7
COMMENTS
A062295 is the sequence of smallest squares such that the pairwise sums of not necessarily distinct elements are all distinct, whereas A133743 is the sequence of smallest squares such that the pairwise sums of distinct elements are all distinct.
LINKS
EXAMPLE
a(7) = A062295(7) - A133743(7) = 64 - 49 = 15.
PROG
(Python)
from collections import deque
from itertools import count, islice
def A133744_gen(): # generator of terms
aset2, alist, bset2, blist, aqueue, bqueue = set(), [], set(), [], deque(), deque()
for k in (n**2 for n in count(1)):
cset2 = {k<<1}
if (k<<1) not in aset2:
for a in alist:
if (m:=a+k) in aset2:
break
cset2.add(m)
else:
aqueue.append(k)
alist.append(k)
aset2.update(cset2)
cset2 = set()
for b in blist:
if (m:=b+k) in bset2:
break
cset2.add(m)
else:
bqueue.append(k)
blist.append(k)
bset2.update(cset2)
if len(aqueue) > 0 and len(bqueue) > 0:
yield aqueue.popleft()-bqueue.popleft()
A133744_list = list(islice(A133744_gen(), 30)) # Chai Wah Wu, Sep 11 2023
CROSSREFS
KEYWORD
sign
AUTHOR
Klaus Brockhaus, Sep 24 2007
STATUS
approved