OFFSET
1,1
COMMENTS
185 = 5*37, 497 = 7*71, 511 = 7*73, 1041 = 3*347, 1059 = 3*353, 1903 = 11*173, 3107 = 13*239, 4705 = 5*941, 4735 = 5*947, 6817 = 17*401, 9481 = 19*499, 12761 = 7*1823, 16721 = 23*727, 33379 = 29*1151, 48961 = 11*4451, 49027 = 11*4457, 68857 = 37*1861, 80561 = 13*6197, 80639 = 13*6203, 93521 = 41*2281.
MATHEMATICA
a[1]=1; a[n_]:=a[n]=a[n-1]+n^(1+Mod[n, 2]); A136047=Table[a[n], {n, 1000}]; A136048=Select[A136047, Total[Last/@FactorInteger[ # ]]==2&]
nxt[{n_, a_}]:={n+1, If[OddQ[n], a+n+1, a+(n+1)^2]}; Select[ Transpose[ NestList[ nxt, {1, 1}, 200]][[2]], PrimeOmega[#]==2&] (* Harvey P. Dale, Oct 11 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Dec 12 2007
STATUS
approved