A080735 a(1)=1, then a(n)=2*a(n-1) if a(n-1) is prime, a(n)=a(n-1)+1 otherwise.
1, 2, 4, 5, 10, 11, 22, 23, 46, 47, 94, 95, 96, 97, 194, 195, 196, 197, 394, 395, 396, 397, 794, 795, 796, 797, 1594, 1595, 1596, 1597, 3194, 3195, 3196, 3197, 3198, 3199, 3200, 3201, 3202, 3203, 6406, 6407, 6408, 6409, 6410, 6411, 6412, 6413, 6414, 6415, 6416
Offset: 1
Keywords
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
NestList[If[PrimeQ[#],2#,#+1]&,1,50] (* Harvey P. Dale, Aug 26 2013 *)
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PARI
u=1; for(n=2,100,v=if(isprime(u),u+1,2*u); u=v; print1(v,","))
Formula
It seems that log(a(n))/sqrt(n) -> C, a constant around 1.3.....
a(n) = A055496(m) when a(n+1) > a(n) + 1. - Bill McEachen, Mar 24 2024
Comments