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A243441
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Primes p such that p + A000120(p) is also a prime, where A000120 = sum of digits in base 2 = Hamming weight.
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9
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2, 3, 5, 17, 43, 163, 277, 311, 347, 373, 461, 479, 571, 643, 673, 821, 853, 857, 881, 977, 983, 1013, 1093, 1103, 1117, 1181, 1223, 1297, 1427, 1433, 1439, 1481, 1523, 1607, 1613, 1621, 1823, 1861, 1871, 1873, 2003, 2083, 2281, 2333, 2393, 2417, 2467, 2549
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OFFSET
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1,1
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LINKS
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EXAMPLE
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2 + digitsum(2,base=2) = 2 + digitsum(10) = 2 + 1 = 3, which is prime.
3 + digitsum(11) = 3 + 2 = 5.
5 + digitsum(101) = 5 + 2 = 7.
17 + digitsum(10001) = 17 + 2 = 19.
43 + digitsum(101011) = 43 + 4 = 47.
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MATHEMATICA
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Select[Prime@ Range@ 400, PrimeQ[# + Total@ IntegerDigits[#, 2]] &] (* Michael De Vlieger, Nov 06 2018 *)
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PROG
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(PARI) lista(lim) = forprime(p=2, lim, if (isprime(p+hammingweight(p)), print1(p, ", "))); \\ Michel Marcus, Jun 10 2014
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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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EXTENSIONS
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STATUS
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approved
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