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A351382
Products of four distinct primes between sphenic numbers (products of 3 distinct primes).
0
7566, 9086, 10506, 15170, 17170, 18734, 18886, 18906, 19670, 20306, 20586, 21594, 21606, 22630, 23218, 23694, 23902, 25070, 25466, 25670, 26466, 26554, 26610, 27714, 28302, 28614, 29562, 30514, 30710, 32054, 32154, 32334, 34238, 34706, 35014, 37114, 38590, 39354
OFFSET
1,1
COMMENTS
Numbers with at least one prime exponent greater than 1 are excluded here.
EXAMPLE
7566 = 2*3*13*97 (between 7565 = 5 * 17 * 89 and 7567 = 7*23*47).
9086 = 2*7*11*59 (between 9085 = 5 * 23 * 79 and 9087 = 3*13*233).
10506 = 2*3*17*103 (between 10505 = 5 * 11 * 191 and 10507 = 7*19*79).
15170 = 2*5*37*41 (between 15169 = 7 * 11 * 197 and 15171 = 3*13*389).
MATHEMATICA
q[n_, m_] := Module[{f = FactorInteger[n]}, Length[f] == m && Max[f[[;; , 2]]] == 1]; Select[Range[40000], q[#, 4] && q[# - 1, 3] && q[# + 1, 3] &] (* Amiram Eldar, Mar 28 2022 *)
CROSSREFS
Cf. A007304.
Sequence in context: A145313 A235961 A235572 * A206173 A205427 A252163
KEYWORD
nonn
AUTHOR
Massimo Kofler, Mar 28 2022
STATUS
approved