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A227888
Smallest odd k such that k*2^n-1, k*2^n-1+2*j, k*2^n-1+4*j or k*2^n-1-2*j, k*2^n-1, k*2^n-1+2*j are consecutive primes in arithmetic progression for some j.
3
3, 1, 19, 3, 19, 273, 93, 113, 87, 35, 31, 143, 31, 15, 315, 779, 207, 347, 91, 327, 291, 351, 195, 39, 1911, 971, 1083, 435, 1345, 593, 183, 1295, 291, 2553, 735, 1113, 31, 131, 61, 209, 379, 567, 2331, 1907, 4429, 23, 453, 1517, 2281, 2187, 1441, 4847, 1975
OFFSET
1,1
LINKS
EXAMPLE
3*2^1-1-2=3 3*2^1-1=5 3*2^1-1+2=7 so a(1)=3.
3*2^4-1=47 3*2^4-1+6=53 3*2^4-1+12=59 so a(4)=3.
CROSSREFS
Cf. A052187.
Sequence in context: A290317 A016480 A086156 * A188109 A247232 A147076
KEYWORD
nonn
AUTHOR
Pierre CAMI, Oct 26 2013
STATUS
approved