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A270391
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"Story primes" (see comments).
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1
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2, 3, 5, 7, 13, 29, 31, 41, 47, 53, 61, 79, 83, 97, 103, 163, 347, 367, 401, 487, 503, 521, 523, 541, 547, 563, 569, 587, 601, 709, 743, 769, 821, 823, 907, 941, 947, 967, 1063, 1069, 1481, 1609, 1621, 1663, 1669, 1847, 2887, 3607, 3863, 4001, 4889, 5003, 5021, 5023, 5081, 5281, 5441
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OFFSET
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1,1
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COMMENTS
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A "story prime" is a prime on top of a descending triangle (such as the ones below) where every "story" is prime:
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6 0 1 1 0 6 3 9 6 2 9
6 1 1 6 3 3 4 7
5 5 3 1 3
2 2
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Each digit "d" must be the absolute difference of the two digits above "d". No leading zeros are accepted at any stage. The biggest such prime is 528888881, with 9 stories. There are only 128 such primes.
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LINKS
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EXAMPLE
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We see that the first 3 of the second row (from top) is the absolute difference between 5 and 2; the next digit is 6, the absolute difference between 2 and 8; etc.
5 2 8 8 8 8 8 8 1
3 6 0 0 0 0 0 7
3 6 0 0 0 0 7
3 6 0 0 0 7
3 6 0 0 7
3 6 0 7
3 6 7
3 1
2
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MATHEMATICA
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Select[Prime@ Range@ 720, Function[k, AllTrue[Most@ NestWhileList[Abs@ Differences@ # &, IntegerDigits@ k, # != {} &], And[First@ # != 0 &@ #, PrimeQ@ FromDigits@ #] &]]] (* Michael De Vlieger, Mar 16 2016, Version 10 *)
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CROSSREFS
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KEYWORD
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nonn,base,fini,full
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AUTHOR
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STATUS
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approved
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