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A117876
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Primes p=prime(k) of level (1,2), i.e., such that A118534(k) = prime(k-2).
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19
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23, 47, 73, 233, 353, 647, 1097, 1283, 1433, 1453, 1493, 1613, 1709, 1889, 2099, 2161, 2383, 2621, 2693, 2713, 3049, 3533, 3559, 3923, 4007, 4133, 4643, 4793, 4937, 5443, 5743, 6101, 7213, 7309, 7351, 7561, 7621, 7829, 8179, 8237, 8719, 8849, 9109, 9343, 9467
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OFFSET
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1,1
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COMMENTS
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If prime(k) has level 1 in A117563, and if 2*prime(k) - prime(k+1) = prime(k-i), then we say that prime(k) has level (1,i). Sequence gives primes of level (1,2).
The prime p(4)=7 cannot be decomposed into weight*level+gap (<=> A117563(4)=0 <=> A118534(4)=0 <=> A117078(4)=0). For all other primes, an equivalent definition would be: Primes p(k) such that 2*p(k) - p(k+1) = p(k-2). - Rémi Eismann and M. F. Hasler, Nov 08 2009
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LINKS
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FORMULA
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EXAMPLE
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29 = 2*23 - 17, 2179 = 2*2161 - 2143, 5749 = 2*5743 - 5737.
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MATHEMATICA
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With[{m = 2}, Prime@ Select[Range[m + 1, 1200], If[MemberQ[{1, 2, 4}, #], 0, 2 Prime[#] - Prime[# + 1]] == Prime[# - m] &]] (* Michael De Vlieger, Jul 16 2017 *)
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PROG
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(PARI) for(n=5, 9999, 2*prime(n)-prime(n+1) == prime(n-2) & print1(prime(n), ", ")) \\ M. F. Hasler, Nov 08 2009
(PARI) is_A117876(p)={ isprime(p) & isprime(d=2*p-nextprime(p+2)) & d == precprime(precprime(p-2)-2) & p>7 } \\ M. F. Hasler, Nov 08 2009
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Definition corrected and terms double-checked by M. F. Hasler, Nov 08 2009
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STATUS
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approved
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