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A082445 Palindromic primes with middle digit 9. 1
191, 797, 13931, 17971, 19991, 71917, 77977, 79997, 94949, 95959, 1129211, 1409041, 1469641, 1489841, 1579751, 1589851, 1609061, 1829281, 1879781, 1909091, 1969691, 3089803, 3319133, 3329233, 3439343, 3449443, 3479743, 3569653, 3589853, 3689863, 3709073, 3769673 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..611 (* All such primes with 9 or fewer digits *)
MATHEMATICA
ppmd9Q[n_]:=Module[{idn=IntegerDigits[n]}, idn==Reverse[idn]&&idn[[(Length[ idn]+1)/2]]==9]; Flatten[Table[Select[Prime[Range[PrimePi[10^(2n)+1], PrimePi[ 10^(2n+1)-1]]], ppmd9Q], {n, 3}]] (* Harvey P. Dale, Feb 11 2015 *)
PROG
(Magma) [ p: p in PrimesUpTo(200000000) | IsOdd(d) and D[(d+1) div 2] eq 9 and D eq Reverse(D) where d is #D where D is Intseq(p) ]; // Vincenzo Librandi, Apr 12 2011
CROSSREFS
Cf. A002385.
Sequence in context: A337791 A347294 A086878 * A108848 A052165 A103733
KEYWORD
nonn,base
AUTHOR
Lekraj Beedassy, Apr 25 2003
EXTENSIONS
a(4), a(14), a(18), a(24), a(27) from Vincenzo Librandi, Apr 12 2011
STATUS
approved

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Last modified March 29 10:44 EDT 2024. Contains 371268 sequences. (Running on oeis4.)