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 A234105 Integers of the form (p*q*r*s - 1)/2, where p, q, r, s are distinct primes. 4
 577, 682, 892, 997, 1072, 1207, 1402, 1501, 1522, 1567, 1627, 1657, 1852, 1897, 1942, 1963, 2152, 2194, 2242, 2257, 2320, 2392, 2422, 2467, 2502, 2557, 2593, 2656, 2782, 2827, 2932, 3022, 3052, 3097, 3139, 3202, 3272, 3277, 3349, 3382, 3391, 3517, 3547, 3580 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..44. FORMULA -1 + A234500. MATHEMATICA t = Select[Range[1, 20000, 2], Map[Last, FactorInteger[#]] == Table[1, {4}] &]; Take[(t - 1)/2, 120] (* A234105 *) v = Flatten[Position[PrimeQ[(t - 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}] (* A234498 *) (w - 1)/2 (* A234499 *) (* Peter J. C. Moses, Dec 23 2013 *) CROSSREFS Cf. A234498, A234499, A234500, A234093, A234097. Sequence in context: A198778 A198777 A104937 * A234499 A218039 A218157 Adjacent sequences: A234102 A234103 A234104 * A234106 A234107 A234108 KEYWORD nonn,easy AUTHOR Clark Kimberling, Jan 01 2014 STATUS approved

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Last modified April 13 11:46 EDT 2024. Contains 371640 sequences. (Running on oeis4.)