|
%I #12 Oct 23 2017 01:23:20
%S 2,6,12,20,15,21,56,72,45,55,44,52,91,35,80,272,153,171,95,35,77,253,
%T 184,200,325,351,189,203,145,155,992,352,187,119,63,333,703,247,104,
%U 328,287,301,473,99,207,1081,752,784,1225,425,221,689,1431,297,88,152,551
%N a(n) = (largest power of a prime dividing n) * (largest power of a prime dividing (n+1)).
%C The largest prime-power dividing 12 is 4. The largest prime power dividing 13 is 13. So a(12) = 4*13 = 52.
%H Michael De Vlieger, <a href="/A139082/b139082.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A034699(n)*A034699(n+1). - _R. J. Mathar_, Apr 16 2008
%p isA000961 := proc(n) if nops(ifactors(n)[2]) =1 then true ; else false ; fi ; end: A034699 := proc(n) local dvs,d ; if n = 1 then RETURN(1) ; fi ; dvs := sort(convert(numtheory[divisors](n),list),`>`) ; for d in dvs do if isA000961(d) then RETURN(d) ; fi ; od: RETURN(0) ; end: A139082 := proc(n) A034699(n)*A034699(n+1) ; end: seq(A139082(n),n=1..100) ; # _R. J. Mathar_, Apr 16 2008
%t Times @@ # & /@ Partition[Array[Max@ Map[Power @@ # &, FactorInteger@ #] &, 58], 2, 1] (* _Michael De Vlieger_, Oct 22 2017 *)
%Y Cf. A139081, A139084.
%K nonn
%O 1,1
%A _Leroy Quet_, Apr 07 2008
%E More terms from _R. J. Mathar_, Apr 16 2008
|
