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 A097570 Least k such that k*prime(n)#/5 - 5 and k*prime(n)#/5 + 5 are consecutive primes with gap 10, where prime(n)# is the n-th primorial. 4
 360, 120, 24, 17, 2, 9, 4, 64, 3, 6, 1, 72, 102, 119, 66, 51, 34, 66, 89, 283, 52, 84, 59, 554, 81, 44, 328, 69, 26, 36, 101, 42, 898, 17, 121, 193, 69, 137, 346, 2, 868, 412, 101, 247, 417, 1732, 206, 2278, 109, 762, 87, 268, 511, 1213, 108, 41, 43, 946, 483, 706, 72 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..61. EXAMPLE 360*2/5=144, 139 and 149 are consecutive primes with gap 10, so a(1) = 360. 120*2*3/5=144, so a(2) = 120. 24*2*3*5/5=144, so a(3) = 24. 17*2*3*5*7/5=714, 709 and 719 are consecutive primes with gap 10, so a(4) = 17. MATHEMATICA a[n_] := Module[{k = 1, p = Product[Prime[i], {i, 1, n}]}, While[!(PrimeQ[k*p/5-5] && NextPrime[k*p/5-5] == k*p/5+5), k++]; k]; Array[a, 60] (* Amiram Eldar, Jul 17 2021 *) CROSSREFS Cf. A002110. Cf. A097439, A097440, A097441, A098064. Sequence in context: A101996 A237017 A360943 * A185641 A352225 A031966 Adjacent sequences: A097567 A097568 A097569 * A097571 A097572 A097573 KEYWORD nonn AUTHOR Pierre CAMI, Aug 28 2004 STATUS approved

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Last modified September 12 11:46 EDT 2024. Contains 375851 sequences. (Running on oeis4.)