The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A173708 Numbers of the form p*(q-1) for primes p, q with p>q. 2
 3, 5, 7, 10, 11, 13, 14, 17, 19, 22, 23, 26, 28, 29, 31, 34, 37, 38, 41, 43, 44, 46, 47, 52, 53, 58, 59, 61, 62, 66, 67, 68, 71, 73, 74, 76, 78, 79, 82, 83, 86, 89, 92, 94, 97, 101, 102, 103, 106, 107, 109, 113, 114, 116, 118, 122, 124, 127, 130, 131 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sorted A173706. Possible values from the formula for crossing numbers of (p,q) torus knots. REFERENCES Peter R. Cromwell, Knots and Links, Cambridge University Press, November 15, 2004, p.255. LINKS Alois P. Heinz, Table of n, a(n) for n = 1..1000 FORMULA {p*(q-1) : p, q prime and p>q}. MAPLE a:= proc(n) option remember;       local k, p, q;       if n=1 then 3       else for k from a(n-1)+1 do              for p in numtheory[factorset](k) do                q:= k/p+1;                if isprime (q) and p>q then return k fi              od            od       fi     end: seq (a(n), n=1..60);  # Alois P. Heinz, Nov 26 2010 CROSSREFS Cf. A000040, A006093, A173706. Sequence in context: A071561 A241561 A241008 * A239929 A246955 A167907 Adjacent sequences:  A173705 A173706 A173707 * A173709 A173710 A173711 KEYWORD nonn,easy AUTHOR Jonathan Vos Post, Nov 25 2010 EXTENSIONS More terms from Alois P. Heinz, Nov 26 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 8 21:44 EDT 2020. Contains 333329 sequences. (Running on oeis4.)