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 A134020 Numbers that are one less than a square and have exactly 4 divisors. 1
 8, 15, 35, 143, 323, 899, 1763, 3599, 5183, 10403, 11663, 19043, 22499, 32399, 36863, 39203, 51983, 57599, 72899, 79523, 97343, 121103, 176399, 186623, 213443, 272483, 324899, 359999, 381923, 412163, 435599, 656099, 675683, 685583, 736163 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A037074 is a subsequence. - R. J. Mathar, Jun 08 2008 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..5400 MAPLE with(numtheory): a:=proc(n) if type(sqrt(n+1), integer)=true and tau(n)=4 then n else end if end proc: seq(a(n), n=1..800000); # Emeric Deutsch, Jan 27 2008 MATHEMATICA t={}; Do[If[DivisorSigma[0, n]==4&&IntegerQ[Sqrt[n+1]], AppendTo[t, n]], {n, 10^6}]; t (* Jayanta Basu, Jun 03 2013 *) CROSSREFS Sequence in context: A293360 A287644 A089954 * A343141 A197602 A306599 Adjacent sequences:  A134017 A134018 A134019 * A134021 A134022 A134023 KEYWORD nonn AUTHOR Giovanni Teofilatto, Jan 11 2008 EXTENSIONS Edited and extended by Emeric Deutsch, Jan 27 2008 Name reworded by Jon E. Schoenfield, Jan 15 2019 STATUS approved

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Last modified July 29 01:22 EDT 2021. Contains 346340 sequences. (Running on oeis4.)