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A088866 Primes where flipping 6 and 9 is also prime. 0
97, 67, 193, 197, 163, 167, 293, 263, 397, 367, 491, 461, 593, 563, 907, 941, 947, 953, 991, 977, 983, 607, 641, 647, 653, 677, 683, 661, 1091, 1093, 1061, 1063, 1193, 1163, 1597, 1567, 1901, 1907, 1913, 1993, 1997, 1601, 1607, 1613, 1663, 1667, 2297, 2267 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Terms ordered according to first prime found but shown after flipping its 6's and 9's. - Harvey P. Dale, Feb 07 2015

The first term that contains both 6's and 9's is 2963. - Harvey P. Dale, Feb 07 2015

LINKS

Table of n, a(n) for n=1..48.

EXAMPLE

991 is prime, flipping the 9's we get 661 which is also prime.

MATHEMATICA

fd96Q[n_]:=Module[{idn=IntegerDigits[n]}, (MemberQ[idn, 6]||MemberQ[idn, 9]) &&PrimeQ[FromDigits[idn/.{6->9, 9->6}]]]; FromDigits[IntegerDigits[#]/.{6->9, 9->6}]&/@Select[Prime[Range[400]], fd96Q] (* Harvey P. Dale, Feb 07 2015 *)

PROG

(PARI) flip69pr(n) = { for(x=1, n, y=x; v=0; v1=0; f=0; ln =length(Str(x)); a = vector(ln); b = vector(ln); forstep(j=ln, 1, -1, r = y%10; a[j]=r; b[j]=r; if(r==6, a[j] = 9; f=1); if(r==9, a[j] = 6; f=1); y = floor(y/10); ); forstep(j=ln, 1, -1, v=v+a[j]*10^(ln-j); v1=v1+b[j]*10^(ln-j); ); if(isprime(v) && isprime(v1) && f, print1(v", ")); ) }

CROSSREFS

Sequence in context: A068830 A033417 A182690 * A244192 A075478 A126146

Adjacent sequences:  A088863 A088864 A088865 * A088867 A088868 A088869

KEYWORD

nonn,base

AUTHOR

Cino Hilliard, Nov 26 2003

STATUS

approved

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Last modified May 18 23:58 EDT 2021. Contains 344009 sequences. (Running on oeis4.)