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.

A264719 Numbers that are greater than the average of their closest flanking primes.

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%I A264719 #11 Nov 25 2015 20:52:38
%S A264719 10,11,16,17,22,27,28,29,35,36,37,40,41,46,51,52,57,58,59,65,66,67,70,
%T A264719 71,77,78,79,82,87,88,94,95,96,97,100,101,106,107,112,121,122,123,124,
%U A264719 125,126,127,130,135,136,137,145,146,147,148,149,155,156,161,162
%N A264719 Numbers that are greater than the average of their closest flanking primes.
%C A264719 Numbers that are nearer to the immediately next prime than to the immediately previous prime.
%C A264719 This sequence may be viewed as a generalization of A051634 (the strong primes) that includes qualifying composite numbers.
%C A264719 The union of this sequence with A264720 & A145025 is A000027 (omitting 1 & 2).
%H A264719 Chris Boyd, <a href="/A264719/b264719.txt">Table of n, a(n) for n = 1..10000</a>
%e A264719 a(11) = 37 because 37 > (31 + 41)/2 = 36.
%e A264719 a(12) = 40 because 40 > (37 + 41)/2 = 37.
%t A264719 Select[Range@ 162, # > (Abs@ NextPrime[#, -1] + NextPrime@ #)/2 &] (* _Michael De Vlieger_, Nov 22 2015 *)
%o A264719 (PARI) test(n)= {if(n-precprime(n-1)>nextprime(n+1)-n&&n>2,return(1),return(0))}
%o A264719 for(i=1,200,if(test(i),print1(i,", ")))
%Y A264719 Cf. A051634, A145025, A264720, A264721, A264722.
%K A264719 nonn,easy
%O A264719 1,1
%A A264719 _Chris Boyd_, Nov 21 2015