A259026 Numbers n such that n*23^n-1 is semiprime.
1, 2, 6, 8, 18, 21, 24, 26, 28, 30, 33, 230
Offset: 1
Links
- K. O'Bryant, Sets of Natural Numbers with Proscribed Subsets, J. Int. Seq. 18 (2015) # 15.7.7
Crossrefs
Similar sequences listed in A242273.
Programs
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Magma
IsSemiprime:=func; [n: n in [2..200] | IsSemiprime(s) where s is n*23^n-1];
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Mathematica
Select[Range[200], PrimeOmega[# 23^# - 1]==2&]
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PARI
isok(n)=bigomega(n*23^n-1)==2 \\ Anders Hellström, Aug 20 2015
Comments