OFFSET
1,2
EXAMPLE
3 + 2 = 5 = a(12),
2 + 2 = 4 = a(13),
5 + 3 = 8 = a(14),
5 + 2 = 7 = a(15),
7 + 2 = 9 = a(16),
11 + 2 = 13 = a(17),
3 + 3 = 6 = a(18),
5 + 2 = 7 = a(19),
2 + 13 = 15 = a(20),
3 + 3 = 6 = a(21),
2 + 2 = 4 = a(22),
7 + 2 = 9 = a(23), etc.
MAPLE
pflat := proc(nmax) local a, ifs, n, p, c ; a := [0, 1] ; for n from 2 to nmax do if not isprime(n) then ifs := ifactors(n)[2] ; for p in ifs do a := [op(a), op(1, p)] ; if op(2, p) > 1 then a := [op(a), op(2, p)] ; fi; od: fi; od: a ; end: L := pflat(300) ; for n from 1 to nops(L)-2 by 2 do printf("%d, ", op(n, L) + op(n+1, L) ) ; end do: # R. J. Mathar, Apr 29 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Nov 20 2008
EXTENSIONS
Corrected (a(15) removed, former a(65) replaced) by R. J. Mathar, Apr 29 2010
STATUS
approved