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A270391 "Story primes" (see comments). 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A "story prime" is a prime on top of a descending triangle (such as the ones below) where every "story" is prime:
.
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
.
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.
LINKS
EXAMPLE
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
MATHEMATICA
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 *)
CROSSREFS
Sequence in context: A158281 A115261 A063792 * A172508 A272107 A227880
KEYWORD
nonn,base,fini,full
AUTHOR
STATUS
approved

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Last modified September 14 16:47 EDT 2024. Contains 375929 sequences. (Running on oeis4.)