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Primes starting and ending with 1.
9

%I #30 Jun 29 2018 03:57:21

%S 11,101,131,151,181,191,1021,1031,1051,1061,1091,1151,1171,1181,1201,

%T 1231,1291,1301,1321,1361,1381,1451,1471,1481,1511,1531,1571,1601,

%U 1621,1721,1741,1801,1811,1831,1861,1871,1901,1931,1951,10061,10091,10111,10141

%N Primes starting and ending with 1.

%C Complement of A208261 (nonprime numbers with all divisors starting and ending with digit 1) with respect to A208262 (numbers with all divisors starting and ending with digit 1). - _Jaroslav Krizek_, Mar 04 2012

%C Intersection of A030430 and A045707. - _Michel Marcus_, Jun 08 2013

%H Harry J. Smith, <a href="/A062332/b062332.txt">Table of n, a(n) for n = 1..1000</a>

%F A010051(a(n)) * A000030(a(n)) * (a(n) mod 10) = 1. - _Reinhard Zumkeller_, Jul 16 2014

%e 102701 is a member as it is a prime and the first and the last digits are both 1.

%t fl1Q[n_]:=Module[{idn=IntegerDigits[n]},First[idn]==Last[idn]==1]; Select[ Prime[Range[1300]],fl1Q] (* _Harvey P. Dale_, Apr 30 2012 *)

%o (PARI) { n=-1; t=log(10); forprime (p=2, 5*10^5, if ((p-10*(p\10)) == 1 && (p\10^(log(p)\t)) == 1, write("b062332.txt", n++, " ", p); if (n==1000, break)) ) } \\ _Harry J. Smith_, Aug 05 2009

%o (Haskell)

%o a062332 n = a062332_list !! (n-1)

%o a062332_list = filter ((== 1) . a010051') a208259_list

%o -- _Reinhard Zumkeller_, Jul 16 2014

%Y Cf. A208259 (Numbers starting and ending with digit 1).

%Y Cf. A010051, A017281, A131835, A000030.

%K nonn,base,easy

%O 1,1

%A _Amarnath Murthy_, Jun 21 2001

%E Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jun 29 2001

%E Missing term a(36)=1901 added by _Harry J. Smith_, Aug 05 2009