A119289 - OEIS

%I #16 Aug 08 2021 11:36:02

%S 53,89,107,113,167,179,251,317,347,389,397,419,431,443,457,461,521,

%T 599,641,643,653,709,727,761,773,797,839,863,887,907,911,977,991,1087,

%U 1091,1103,1153,1187,1213,1217,1229,1231,1259,1277,1283,1301,1307,1319,1327

%N Prime numbers p such that there is no prime between 10*p and 10*p+9 inclusive.

%C Prime numbers p with property that appending any single decimal digit to p does not produce a prime. Prime members of A032352.

%H Michael S. Branicky, <a href="/A119289/b119289.txt">Table of n, a(n) for n = 1..10000</a>

%p a:=proc(n) if isprime(n) = true and isprime(10*n+1)=false and isprime(10*n+3)=false and isprime(10*n+5)=false and isprime(10*n+7)=false and isprime(10*n+9)=false then n else fi end: seq(a(n),n=1..1500); # _Emeric Deutsch_, Jul 24 2006

%t Select[Prime[Range[1000]], PrimePi[10# + 9] - PrimePi[10# ] == 0 &] (* _Stefan Steinerberger_, Jul 24 2006 *)

%o (PARI) lista(nn) = {forprime(p=2, nn, if (primepi(10*p+9) - primepi(10*p) == 0, print1(p, ", ")););} \\ _Michel Marcus_, Jun 23 2015

%o (Python)

%o from sympy import isprime, primerange

%o def ok(p): s = str(p); return all(not isprime(int(s+d)) for d in "1379")

%o print(list(filter(ok, primerange(1, 1328)))) # _Michael S. Branicky_, Aug 08 2021

%Y Supersequence of A239747.

%K base,nonn

%O 1,1

%A _Tanya Khovanova_, Jul 23 2006

%E More terms sent by several contributors, Jul 23 2006