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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;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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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
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LINKS
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Michael De Vlieger, Table of n, a(n) for n = 1..1000
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FORMULA
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a(n) = Min{x : sigma_4n(x) mod x = 0, x > 1}
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EXAMPLE
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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:
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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)
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MATHEMATICA
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Table[m = 2; While[Mod[DivisorSigma[4 n, m], m] > 0, m++]; m, {n, 66}] (* Michael De Vlieger, Jul 17 2017 *)
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PROG
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(PARI) a(n) = {n *= 4; my(m = 2); while (sigma(m, n) % m, m++); m; } \\ Michel Marcus, Oct 02 2016
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CROSSREFS
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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
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KEYWORD
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nonn
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AUTHOR
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Labos Elemer, Dec 11 2001
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STATUS
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approved
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