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 A118860 Numbers k such that k-1, k+1, 2k-1, 2k+1, 3k-1, 3k+1, 4k-1 and 4k+1 are all primes. 6
 21968100, 37674210, 81875220, 356467230, 416172330, 750662640, 1007393730, 1150070040, 1586271960, 1963954650, 3127171320, 3669568560, 4377895410, 4383541050, 5575083360, 5686935870, 5708418870, 7365234450, 7478474430, 7681046100, 8453862690, 8898688680 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All terms are multiples of 210, hence simpler code is possible. LINKS Table of n, a(n) for n=1..22. EXAMPLE 21968100 is there because 21968099, 21968101, 43936199, 43936201, 65904299, 65904301, 87872399, 87872401 are all prime. MATHEMATICA tb={}; Do[If[(PrimeQ[n-1]&&PrimeQ[n+1])&& (PrimeQ[2*n-1]&&PrimeQ[2*n+1])&& (PrimeQ[3*n-1]&&PrimeQ[3*n+1])&& (PrimeQ[4*n-1]&&PrimeQ[4*n+1]), Print[n]; AppendTo[tb, n]], {n, 21968100, 10^8, 210}]; tb CROSSREFS Cf. A014574, A066388, A118859, A349321, A348348. Sequence in context: A251998 A210389 A364435 * A186595 A210076 A184375 Adjacent sequences: A118857 A118858 A118859 * A118861 A118862 A118863 KEYWORD nonn AUTHOR Labos Elemer, May 03 2006 EXTENSIONS Edited by Don Reble, May 16 2006 a(20)-a(22) from Pontus von Brömssen, Oct 14 2021 STATUS approved

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Last modified December 1 23:26 EST 2023. Contains 367503 sequences. (Running on oeis4.)