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A066284 a(n) = A066135(4*n). 5
34, 84, 34, 84, 34, 194, 34, 84, 34, 84, 34, 228, 34, 84, 34, 84, 34, 194, 34, 84, 34, 84, 34, 228, 34, 84, 34, 84, 34, 194, 34, 84, 34, 84, 34, 386, 34, 84, 34, 84, 34, 194, 34, 84, 34, 84, 34, 228, 34, 84, 34, 84, 34, 194, 34, 84, 34, 84, 34, 228, 34, 84, 34, 84, 34, 194 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) <= 2p, where p = A002586(4n) is the least prime factor of (1 + 16^n). (See the Comment in A066135.) - Jonathan Sondow, Nov 23 2012

LINKS

Michael De Vlieger, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = Min{x : sigma_4n(x) mod x = 0, x > 1}

EXAMPLE

First 3 terms correspond to entries of other sequences as follows: a(1)=A046763(2), a(2)=A055712(2), a(3)=A055716(2).

From Michael De Vlieger, Jul 17 2017: (Start)

First position of values, with observations pertaining to values for 1 <= n <= 3000:

    Value   Position   Observations:

    --------------------------------

       34     1        All odd.

       84     2        In A047235.

      194     6        In A017593.

      228    12

      386    36

     1282    72

     1538   144

     3084   288

   147468   576

     1956   864

  1046532  1152

    24578  2304

     3252  2880

(End)

MATHEMATICA

Table[m = 2; While[Mod[DivisorSigma[4 n, m], m] > 0, m++]; m, {n, 66}] (* Michael De Vlieger, Jul 17 2017 *)

PROG

(PARI) a(n) = {n *= 4; my(m = 2); while (sigma(m, n) % m, m++); m; } \\ Michel Marcus, Oct 02 2016

CROSSREFS

Cf. A066135, A046761, A046762, A046763, A055709-A055717, A007691, A001159.

Sequence in context: A066944 A044172 A044553 * A036199 A092223 A046764

Adjacent sequences:  A066281 A066282 A066283 * A066285 A066286 A066287

KEYWORD

nonn,changed

AUTHOR

Labos Elemer, Dec 11 2001

STATUS

approved

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Last modified July 23 18:47 EDT 2017. Contains 289690 sequences.