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A143704
(1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5, ...) becomes ((1+2)*3, (2+2)*5, (2+3)*7, (2+3)*3, (2+2)*5, (11+2)*2, (3+13)*2, (7+3)*5, ...).
1
9, 20, 35, 15, 20, 26, 32, 50, 102, 10, 42, 56, 299, 15, 14, 48, 28, 93, 72, 88, 95, 18, 185, 63, 45, 92, 430, 44, 25, 1175, 18, 18, 21, 38, 132, 30, 39, 190, 1829, 12, 132, 68, 54, 36, 938, 68, 52, 852, 15, 150, 200, 8, 286, 65, 324, 32, 3569, 12, 204, 135, 93, 200, 25, 40
OFFSET
1,1
LINKS
EXAMPLE
a(8) = ( 7 + 3) * 5 = 10*5 = 50;
a(9) = ( 2 + 4) * 17 = 102;
a(10) = ( 2 + 3) * 2 = 10;
a(11) = (19 + 2) * 2 = 42;
a(12) = ( 5 + 3) * 7 = 56;
a(13) = ( 2 + 11) * 23 = 199;
etc.
MAPLE
g:= proc(n) local L; L:= sort(ifactors(n)[2], (s, t) -> s[1]<t[1]);
L:= map(proc(t) if t[2]=1 then t[1] else op(t) fi end proc, L);
op(L);
end proc:
g(1):= 1:
B:= map(g, [$1..100]):
seq((B[3*i+1]+B[3*i+2])*B[3*i+3], i=0..(nops(B)-3)/3); # Robert Israel, Nov 16 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected (199 replaced by 299, 60 replaced by 30, 549 replaced by 54 etc.) by R. J. Mathar, Apr 18 2010
STATUS
approved