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A046884
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Doubly automorphic primes: p is k-th prime, ends in k and k is itself prime.
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1
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OFFSET
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1,1
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LINKS
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EXAMPLE
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p(7)=17 with 7 and 17 both primes. p(9551)=99551 with both 9551 and 99551 primes.
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MATHEMATICA
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Select[Prime[Prime[Range[6000000]]], PrimePi[#]==Mod[ #, 10^IntegerLength[ PrimePi[#]]]&] (* The program takes a long time to run *) (* Harvey P. Dale, Jul 05 2012 *)
Prime[Select[Range[5517973], PrimeQ[#]&&StringEndsQ[ToString[Prime[#]], ToString[#]]&]] (* Much faster *) (* Ivan N. Ianakiev, Mar 23 2022 *)
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CROSSREFS
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KEYWORD
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base,hard,nice,nonn
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AUTHOR
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STATUS
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approved
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