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A256520 Number of primes between the n-th and (n+1)-st Carmichael numbers. 1
83, 84, 95, 46, 443, 255, 182, 557, 1341, 1107, 526, 553, 923, 114, 1014, 2255, 1278, 880, 3039, 796, 1364, 5212, 2070, 1252, 1614, 1544, 496, 4554, 837, 3013, 3051, 1788, 1430, 1628, 7786, 160, 839, 5825, 5682, 941, 1066, 10506, 1977, 655, 1232, 2288, 4989 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MATHEMATICA
lst = Cases[Range[1, 100000, 2], n_ /; Mod[n, CarmichaelLambda@ n] == 1 && ! PrimeQ@ n]; Reap@ For[k = 1, k < Length@ lst, k++, Sow@ Count[Range[lst[[k]], lst[[k + 1]]], _?PrimeQ]] // Flatten // Rest (* Michael De Vlieger, Apr 03 2015, after Artur Jasinski at A002997 *)
PROG
(PARI) vi=readvec("b002997.txt")
a(n)=primepi(vi[n+1])-primepi(vi[n])
CROSSREFS
Cf. A002997.
Sequence in context: A106418 A031961 A108751 * A130286 A226380 A062677
KEYWORD
nonn
AUTHOR
Felix Fröhlich, Apr 01 2015
STATUS
approved

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Last modified May 26 13:17 EDT 2024. Contains 372826 sequences. (Running on oeis4.)