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!)
A123134 a(n) = prime(n)*(prime(n+1) + 1). 5

%I #29 Sep 08 2022 08:45:28

%S 8,18,40,84,154,234,340,456,690,928,1178,1554,1804,2064,2538,3180,

%T 3658,4148,4824,5254,5840,6636,7470,8722,9894,10504,11124,11770,12426,

%U 14464,16764,18078,19180,20850,22648,23858,25748,27384,29058,31140,32578

%N a(n) = prime(n)*(prime(n+1) + 1).

%C All terms are even. - _Michel Marcus_, Apr 02 2017

%H G. C. Greubel, <a href="/A123134/b123134.txt">Table of n, a(n) for n = 1..1000</a>

%H A. Frank & P. Jacqueroux, <a href="http://www.paulcooijmans.com/others/intcontest.pdf">International Contest</a>, 2001. Item 21

%F a(n) = A000040(n)*A008864(n+1). - _Zak Seidov_, Apr 02 2017

%F a(n) = A286624(n) - 1. - _Antti Karttunen_, Jul 06 2017

%e a(1) = 2*(3+1) = 8, a(2) = 3*(5+1) = 18, a(3) = 5*(7+1) = 40, ...

%t a[n_]:=Prime[n](Prime[n+1]+1); Array[a, 80] (* _Giovanni Resta_, Apr 02 2017 *)

%t #[[1]](#[[2]]+1)&/@Partition[Prime[Range[50]],2,1] (* _Harvey P. Dale_, Jan 06 2019 *)

%o (PARI) for(n=1,100,print1(prime(n)*(prime(n+1)+1),","))

%o (Python)

%o from sympy import prime

%o def a(n): return prime(n) * (prime(n + 1) + 1) # _Indranil Ghosh_, Apr 02 2017

%o (Magma) [NthPrime(n)*(NthPrime(n+1) +1): n in [1..40]]; // _G. C. Greubel_, Aug 04 2021

%Y Cf. A000040, A008864, A286624.

%K nonn

%O 1,1

%A Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 30 2006

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 August 1 18:25 EDT 2024. Contains 374818 sequences. (Running on oeis4.)