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 A088998 Flip 6,9 primes. 0
 19, 29, 59, 97, 79, 89, 61, 67, 109, 139, 149, 191, 193, 199, 197, 179, 163, 167, 229, 239, 293, 263, 269, 349, 359, 397, 379, 389, 367, 409, 419, 439, 449, 491, 499, 479, 461, 463, 467, 509, 593, 599, 563, 569, 907, 911, 919, 929, 937, 941, 947, 953, 991 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Surely these are infinite? LINKS FORMULA For digits d of n if d=6 make it 9 else if d=9 make it 6 and test for prime() EXAMPLE 76 -> 79 prime PROG (PARI) flip69pr(n) = { for(x=1, n, y=x; v=0; f=0; ln =length(Str(x)); a = vector(ln); forstep(j=ln, 1, -1, r = y%10; a[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) ); if(isprime(v) && f, print1(v", ")); ) } CROSSREFS Sequence in context: A090148 A287313 A136071 * A181606 A139886 A089724 Adjacent sequences:  A088995 A088996 A088997 * A088999 A089000 A089001 KEYWORD nonn,base AUTHOR Cino Hilliard, Nov 02 2003 STATUS approved

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