A078553 Largest prime dividing sigma(4,n).

17, 41, 13, 313, 41, 1201, 257, 73, 313, 7321, 41, 14281, 1201, 313, 41, 41761, 73, 3833, 313, 1201, 7321, 139921, 257, 601, 14281, 193, 1201, 353641, 313, 1129, 241, 7321, 41761, 1201, 73, 10529, 3833, 14281, 313, 10313, 1201, 521, 7321, 313

Offset

2,1

Links

Amiram Eldar, Table of n, a(n) for n = 2..10000

Formula

a(n) = A006530(A001159(n)).

Example

Observe nontrivial frequent occurrence of several primes like 73,313,14281, etc.

Mathematica

gpf[n_] := FactorInteger[n][[-1, 1]]; a[n_] := gpf[DivisorSigma[4, n]]; Array[a, 50, 2] (* Amiram Eldar, Aug 01 2019 *)

Crossrefs

Cf. A006530, A001157-A001160, A071190.

Sequence in context: A346527 A152817 A259683 * A104043 A076330 A087658

Adjacent sequences: A078550 A078551 A078552 * A078554 A078555 A078556

Keyword

nonn

Author

Labos Elemer, Dec 05 2002

Status

approved