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 A250293 Primes p such that p#+1 is a semiprime, where # is the primorial. 0
 13, 19, 23, 43, 61, 67, 73, 83, 101, 139, 151, 173, 223, 251, 383 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS First unknown: 457. LINKS Hisanori Mishima, Factorizations of many number sequences EXAMPLE a(1) = 13 so 13# + 1 = 30031 = 59 * 509 is a semiprime. MATHEMATICA Prime[#]&/@(Module[{pmrl=FoldList[Times, Prime[Range[50]]]}, Position[ pmrl, _?(PrimeOmega[ #+1]==2&)]]//Flatten) (* Harvey P. Dale, Apr 29 2017 *) CROSSREFS Cf. A005234, A006862, A078778. Sequence in context: A121877 A109902 A214031 * A058898 A227092 A123840 Adjacent sequences:  A250290 A250291 A250292 * A250294 A250295 A250296 KEYWORD nonn AUTHOR Eric Chen, Dec 24 2014 STATUS approved

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Last modified December 10 12:22 EST 2019. Contains 329895 sequences. (Running on oeis4.)