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A259032
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Numbers n such that digital root of n is 2*(digital root of n-th prime).
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2
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29, 38, 40, 44, 49, 80, 143, 148, 166, 191, 197, 233, 251, 269, 272, 283, 305, 314, 326, 335, 364, 371, 373, 389, 425, 427, 431, 461, 470, 497, 515, 517, 553, 557, 562, 602, 614, 616, 625, 634, 638, 647, 652, 656, 659, 661, 677, 683, 692, 731, 749, 758, 800, 812, 845, 863, 908
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OFFSET
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1,1
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COMMENTS
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Corresponding primes:
109, 163, 173, 193, 227, 409, 823, 857, 983, 1153, 1201, 1471, 1597, 1723, 1747, 1847, 2011, 2083, 2161, 2251, 2459, 2539, 2549, 2683, 2953, 2963, 3001, 3259, 3331, 3547, 3691, 3701, 4007, 4027, 4079, 4423, 4519, 4547, 4637, 4691, 4729, 4801, 4871, 4909, 4933, 4943, 5059, 5107, 5197.
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LINKS
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MATHEMATICA
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Reap[Do[If[FixedPoint[Total[IntegerDigits[#]]&, n]==2*Mod[Prime[n], 9], Sow[n]], {n, 1000}]][[2, 1]]
Select[Range@ 1000, FixedPoint[Total@ IntegerDigits@ # &, #] == 2 FixedPoint[Total@ IntegerDigits@ # &, Prime@ #] &] (* Michael De Vlieger, Jun 19 2015 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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