OFFSET
1,1
COMMENTS
Factorize n to its full extent into the list 1, 2, 3, 2*2, 5, 2*3, 7, 2*2*2, 3*3, 2*5, 11, 2*2*3,..
Remove delimiting commas and the multiplication signs and build new sums by pairing consecutive pairs of numbers of this list, 1+2, 3+2, 2+5, 2+3, 7+2, 2+2, 3+3, 2+5, 11+2, 2+3.. to construct the sequence.
MAPLE
pflat := proc(nmax) local a, ifs, n, p, c ; a := [1] ; for n from 2 to nmax do ifs := ifactors(n)[2] ; for p in ifs do q := op(1, p) ; for c from 1 to op(2, p) do a := [op(a), q] ; od: od: od: a ; end: pL := pflat(90) : for n from 1 to nops(pL)-2 by 2 do printf("%d, ", op(n, pL)+op(n+1, pL)) ; od: # R. J. Mathar, Aug 21 2008
MATHEMATICA
f[n_] := Flatten[ Table[ First@#, {Last@#}] & /@ FactorInteger@n]; Plus @@@ Partition[ Flatten@ Array[f, 74], 2] (* Robert G. Wilson v, Aug 31 2008 *)
CROSSREFS
KEYWORD
nonn,less
AUTHOR
Juri-Stepan Gerasimov, Aug 17 2008
EXTENSIONS
Edited, corrected and extended by R. J. Mathar, Aug 21 2008
STATUS
approved