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 A126850 a(n) = OrdinaryUnitarySigma(a(n-1)). 1

%I

%S 2,3,4,7,8,15,24,60,168,480,1512,3360,12096,28448,64512,163760,401760,

%T 991872,2399040,6858000,13999104,32752000,69400800,172186560,

%U 517867392,1666990080,5662137600,14475575296,33946612000,73359820800,158022774000

%N a(n) = OrdinaryUnitarySigma(a(n-1)).

%F a(n)= A107749(a(n-1)). - _R. J. Mathar_, Jun 15 2008

%p A034448 := proc(n) local ifs,d ; if n = 1 then 1; else ifs := ifactors(n)[2] ; mul(1+ op(1,op(d,ifs))^op(2,op(d,ifs)),d=1..nops(ifs)) ; fi ; end: A006519 := proc(n) local i ; for i in ifactors(n)[2] do if op(1,i) = 2 then RETURN( op(1,i)^op(2,i) ) ; fi ; od: RETURN(1) ; end: A107749 := proc(n) local p2 ; p2 := A006519(n) ; numtheory[sigma](p2)*A034448(n/p2) ; end: A126850 := proc(n) option remember ; if n = 1 then 2; else A107749(A126850(n-1)) ; fi ; end: seq(A126850(n),n=1..40) ; # _R. J. Mathar_, Jun 15 2008

%Y Cf. A107749, A126849.

%Y Cf. A107749, A126849, A007497.

%K nonn

%O 2,1

%A _Yasutoshi Kohmoto_, Feb 24 2007

%E Edited and extended by _R. J. Mathar_, Jun 15 2008

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Last modified May 29 04:33 EDT 2020. Contains 334697 sequences. (Running on oeis4.)