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A243441 Primes p such that p + A000120(p) is also a prime, where A000120 = sum of digits in base 2 = Hamming weight. 9
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
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.
MATHEMATICA
Select[Prime@ Range@ 400, PrimeQ[# + Total@ IntegerDigits[#, 2]] &] (* Michael De Vlieger, Nov 06 2018 *)
PROG
(PARI) lista(lim) = forprime(p=2, lim, if (isprime(p+hammingweight(p)), print1(p, ", "))); \\ Michel Marcus, Jun 10 2014
CROSSREFS
Cf. A000120, A092391 (n + A000120(n)), A048519 (analog for base 10).
Cf. A243442 (analog for p - A000120(p)).
Sequence in context: A211972 A339855 A076706 * A256426 A019350 A235630
KEYWORD
nonn,base
AUTHOR
Anthony Sand, Jun 05 2014
EXTENSIONS
Name edited by M. F. Hasler, Nov 07 2018
STATUS
approved

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Last modified March 28 12:26 EDT 2024. Contains 371254 sequences. (Running on oeis4.)