cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A201822 Numbers k such that 90*k + 77 is prime.

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%I A201822 #17 Sep 08 2022 08:46:01
%S A201822 1,2,3,6,8,9,10,15,17,18,19,20,24,26,29,30,32,34,37,40,41,43,45,46,48,
%T A201822 54,58,59,60,62,65,68,69,74,75,76,79,82,83,85,86,87,89,93,94,95,97,
%U A201822 102,104,109,111,113,114,115,117,122,128,130,131,135,138,144
%N A201822 Numbers k such that 90*k + 77 is prime.
%C A201822 Looking at the format 90k+77 modulo 9 and modulo 10 we see that all entries of A142329 have digital root 5 and last digit 7. (Reverting the process is an application of the Chinese remainder theorem.)
%H A201822 Vincenzo Librandi, <a href="/A201822/b201822.txt">Table of n, a(n) for n = 1..10000</a>
%F A201822 a(n) = (A142329(n) - 77)/90.
%t A201822 Select[Range[0,400],PrimeQ[90 #+77]&] (* _Vincenzo Librandi_, Dec 11 2011 *)
%o A201822 (Magma) [n: n in [0..200] | IsPrime(90*n+77)]; // _Vincenzo Librandi_, Dec 11 2011
%o A201822 (PARI) is(n)=isprime(90*n+77) \\ _Charles R Greathouse IV_, Feb 17 2017
%Y A201822 Cf. A181732, A198382, A195993, A196000, A196007, A201739, A201734, A201804, A201816, A201817, A201818, A201820.
%K A201822 nonn,easy
%O A201822 1,2
%A A201822 _J. W. Helkenberg_, Dec 05 2011