login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A090468 Class 13+ primes. 9

%I #10 Jan 13 2014 12:14:30

%S 545587687,852480757,1048438561,1150849009,1323457987,1745980517,

%T 1756123441,1785398401,1798736161,1892507347,1937020021,2002155601,

%U 2136716521,2150905573,2229004913,2548101601,2671514917,2838761021

%N Class 13+ primes.

%D R. K. Guy, Unsolved Problems in Number Theory, A18.

%H M. F. Hasler, <a href="/A090468/b090468.txt">Table of n, a(n) for n=1..850</a>

%p For Maple program see Mathar link in A005105.

%t PrimeFactors[n_Integer] := Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[n]]; f[n_Integer] := Block[{m = n}, If[m == 0, m = 1, While[ IntegerQ[m/2], m /= 2]; While[ IntegerQ[m/3], m /= 3]]; Apply[Times, PrimeFactors[m] + 1]]; ClassPlusNbr[n_] := Length[ NestWhileList[f, n, UnsameQ, All]] - 3; Prime[ Select[ Range[195000000], ClassPlusNbr[ Prime[ # ]] == 13 &]]

%Y Cf. A005113, A005105 - A005108, A081633 - A081639, A084071, A129474.

%K nonn

%O 1,1

%A _Robert G. Wilson v_, Nov 26 2003

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 04:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)