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Search: id:A088998
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| 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; listen)
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OFFSET
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1,1
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COMMENT
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Surely these are infinite?
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FORMULA
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For digits d of n if d=6 make it 9 else if d=9 make it 6 and test for prime()
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EXAMPLE
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76 -> 79 prime
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PROGRAM
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(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", ")); ) }
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CROSSREFS
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Sequence in context: A141311 A090148 A136071 this_sequence A139886 A089724 A038542
Adjacent sequences: A088995 A088996 A088997 this_sequence A088999 A089000 A089001
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KEYWORD
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nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Nov 02 2003
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