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A234102 Integers of the form (p*q*r + 1)/2, where p, q, r are distinct primes. 6
53, 83, 98, 116, 128, 137, 143, 173, 179, 193, 200, 215, 218, 228, 233, 242, 278, 281, 298, 305, 308, 314, 323, 326, 332, 333, 353, 358, 371, 380, 389, 398, 403, 431, 443, 449, 452, 458, 468, 479, 485, 494, 501, 503, 508, 512, 523, 533, 543, 548, 553, 557 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
1 + A234099.
EXAMPLE
53 = (3*5*7 + 1)/2.
MATHEMATICA
t = Select[Range[1, 10000, 2], Map[Last, FactorInteger[#]] == Table[1, {3}] &]; Take[(t + 1)/2, 120] (* A234102 *)
v = Flatten[Position[PrimeQ[(t + 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}] (* A234103 *)
(w + 1)/2 (* A234104 *) (* Peter J. C. Moses, Dec 23 2013 *)
CROSSREFS
Sequence in context: A125876 A136065 A354915 * A234104 A212420 A001836
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Dec 27 2013
STATUS
approved

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Last modified March 29 05:48 EDT 2024. Contains 371265 sequences. (Running on oeis4.)