A139082 a(n) = (largest power of a prime dividing n) * (largest power of a prime dividing (n+1)).

2, 6, 12, 20, 15, 21, 56, 72, 45, 55, 44, 52, 91, 35, 80, 272, 153, 171, 95, 35, 77, 253, 184, 200, 325, 351, 189, 203, 145, 155, 992, 352, 187, 119, 63, 333, 703, 247, 104, 328, 287, 301, 473, 99, 207, 1081, 752, 784, 1225, 425, 221, 689, 1431, 297, 88, 152, 551

Offset: 1

Author

Leroy Quet, Apr 07 2008

Keywords

• nonn

Comments

The largest prime-power dividing 12 is 4. The largest prime power dividing 13 is 13. So a(12) = 4*13 = 52.

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A139081, A139084.

Programs

Maple

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

Mathematica

Times @@ # & /@ Partition[Array[Max@ Map[Power @@ # &, FactorInteger@ #] &, 58], 2, 1] (* Michael De Vlieger, Oct 22 2017 *)

Formula

a(n) = A034699(n)*A034699(n+1). - R. J. Mathar, Apr 16 2008

Extensions

More terms from R. J. Mathar, Apr 16 2008