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A101783 Lower bound twin primes such that their digital reverse is prime and a lower bound twin prime. 1
3, 5, 11, 17, 71, 101, 191, 1031, 1301, 7349, 7457, 7547, 7589, 9437, 9857, 10007, 10067, 10301, 10457, 10859, 11057, 11717, 11777, 11939, 12107, 12821, 13931, 14081, 14549, 14591, 16061, 16361, 16829, 17417, 18041, 19541, 19697, 19991 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..2500

EXAMPLE

17 is a lower bound twin prime and the reverse,71, is prime and also a lower bound twin prime.

MATHEMATICA

lbtpQ[n_]:=Module[{rp=FromDigits[Reverse[IntegerDigits[n]]]}, PrimeQ[rp] &&PrimeQ[rp+2]]; Select[Transpose[Select[Partition[Prime[Range[2300]], 2, 1], Last[#]-First[#]==2&]][[1]], lbtpQ] (* Harvey P. Dale, Jan 27 2012 *)

PROG

(PARI) twlrpr2(n) = { for(x=1, n, y=twinl(x); z=eval(rev(y)); if(isprime(z) && isprime(z+2), print1(y", ")) ) } twinl(n) = \The n-th upper twin prime { local(c, x); c=0; x=1; while(c<n, if(isprime(prime(x)+2), c++); x++; ); return(prime(x)) }

rev(str) = \\ Get the reverse of the input string

{ local(tmp, s, j); tmp = Vec(Str(str)); s=""; forstep(j=length(tmp), 1, -1, s=concat(s, tmp[j])); return(s) }

CROSSREFS

Sequence in context: A283399 A216181 A101781 * A078883 A155990 A109556

Adjacent sequences:  A101780 A101781 A101782 * A101784 A101785 A101786

KEYWORD

easy,nonn,base

AUTHOR

Cino Hilliard, Jan 26 2005

STATUS

approved

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Last modified August 24 03:51 EDT 2019. Contains 326260 sequences. (Running on oeis4.)