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A143704
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(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, ...).
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1
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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
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OFFSET
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1,1
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LINKS
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EXAMPLE
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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.
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MAPLE
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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
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Corrected (199 replaced by 299, 60 replaced by 30, 549 replaced by 54 etc.) by R. J. Mathar, Apr 18 2010
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STATUS
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approved
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