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A258876
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Integers n such that both n and prime(n) have the same digital root.
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6
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25, 32, 46, 56, 70, 88, 92, 98, 100, 113, 121, 130, 145, 146, 152, 175, 176, 182, 185, 206, 209, 212, 218, 227, 236, 239, 244, 248, 274, 293, 295, 301, 316, 317, 320, 323, 331, 338, 350, 352, 355, 362, 377, 386, 394, 397, 398, 406, 409, 413, 439
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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Both 25 and prime(25) = 97 have 7 for a digital root.
Both 32 and prime(32) = 131 have 5 for a digital root.
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MATHEMATICA
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Reap[Do[If[FixedPoint[Total[IntegerDigits[#]] &, n] == Mod[Prime[n], 9], Sow[n]], {n, 439}]][[2, 1]] (* Seidov *)
Select[Range[500], Mod[#, 9] == Mod[Prime[#], 9] &] (* Alonso del Arte, Jun 17 2015 *)
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PROG
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(PARI) isok(n) = (n % 9) == (prime(n) % 9); \\ Michel Marcus, Jun 17 2015
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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