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A176112
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Primes that take a prime number of steps to reach 1 under the Collatz function.
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2
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3, 5, 41, 43, 53, 61, 109, 139, 149, 163, 167, 173, 179, 227, 233, 269, 307, 317, 373, 401, 439, 443, 479, 541, 557, 563, 607, 617, 619, 661, 751, 787, 827, 863, 911, 937, 1069, 1087, 1093, 1097, 1193, 1259, 1297, 1303, 1321, 1373, 1381, 1409, 1439
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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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MATHEMATICA
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pnsQ[n_]:=PrimeQ[Length[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #>1&]]- 1]; Select[Prime[Range[500]], pnsQ] (* Harvey P. Dale, Nov 28 2016 *)
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PROG
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(PARI) A006577(n)=my(s); while(n>1, n=if(n%2, 3*n+1, n/2); s++); s
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Kent Edward Hays (hayske(AT)gmail.com), Apr 08 2010
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STATUS
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approved
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