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A335859
Terms of A334245 in increasing order and without repetition.
2
12, 15, 21, 30, 35, 57, 60, 65, 70, 77, 91, 105, 111, 114, 119, 126, 133, 143, 147, 150, 155, 165, 168, 180, 185, 190, 198, 209, 217, 220, 231, 234, 255, 260, 264, 294, 301, 310, 312, 319, 323, 330, 341, 360, 427, 432, 437, 455, 456, 462, 473, 497, 504, 510, 511, 546, 559, 588
OFFSET
1,1
COMMENTS
See the network with the 50 smallest merging points of A334245 in link.
LINKS
Bernard Schott and Blandine Schott, Network of merging points.
EXAMPLE
l means: add least prime factor, and,
L means: add largest prime factor.
For 3:
L: 3 + 3 = 6 l: 3 + 3 = 6
l: 6 + 2 = 8 L: 6 + 3 = 9
L: 8 + 2 = 10 l: 9 + 3 = 12
l: 10 + 2 = 12
So A334245(3) = 12 and 12 is a merging point with a(1) = 12.
Now, for 12:
L: 12 + 3 = 15 l: 12 + 2 = 14
l: 15 + 3 = 18 L: 14 + 7 = 21
L: 18 + 3 = 21
So A334245(12) = 21 and 21 is the merging point corresponding to 12 with a(3) = 21.
MAPLE
N:= 1000: # to get all values <= N
S:= x -> x + min(numtheory:-factorset(x)):
T:= x -> x + max(numtheory:-factorset(x)):
f:= proc(n) g(S(n), T(n), 0, 1) end proc:
g:= proc(s, t, i, j) option remember;
if max(s, t) > N then return 0 fi;
if s = t and i=j then return s fi;
if s <= t then
if i = 0 then procname(T(s), t, 1, j)
else procname(S(s), t, 0, j)
fi
elif j=0 then procname(s, T(t), i, 1)
else procname(s, S(t), i, 0)
fi
end proc:
sort(convert(map(f, {$2..N}) minus {0}, list)); # Robert Israel, Jul 09 2020
CROSSREFS
Cf. A334245.
Sequence in context: A162820 A267195 A353702 * A259040 A158190 A122040
KEYWORD
nonn
AUTHOR
Bernard Schott, Jun 27 2020
STATUS
approved