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.

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

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