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A100364
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Numbers n such that the numbers of divisors of n,n+1,n+2 and n+3 are k,2k,4k,8k respectively for some k.
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2
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613, 757, 997, 1237, 2917, 6133, 9853, 15733, 19477, 22501, 24421, 25237, 26293, 26437, 28117, 31477, 33301, 35317, 44101, 45061, 46357, 51637, 53077, 56701, 59221, 61653, 61717, 64381, 65917, 66853, 68583, 70501, 70887, 72901, 75133
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| n=613,614,615,616 have 2,4,8,16 divisors respectively.
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MATHEMATICA
| d0[x_] :=DivisorSigma[0, x]; ta={{0}}; Do[g=n; s=d0[n]; s1=d0[n+1]; s2=d0[n+2]; s3=d0[n+3] If[Equal[s1, 2*s]&&Equal[s2, 4*s]&&Equal[s3, 8*s], ta=Append[ta, n]; Print[{n, s, s1, s2, s3}]], {n, 1, 1000000}]; {ta=Delete[ta, 1], g}
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CROSSREFS
| Cf. A000005, A063446, A100363.
Sequence in context: A107513 A151592 A159641 * A142435 A090869 A020372
Adjacent sequences: A100361 A100362 A100363 * A100365 A100366 A100367
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Nov 19 2004
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