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A107450
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Additive persistence of the prime numbers.
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1
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0, 0, 0, 0, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 2, 2, 1, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 1, 1, 2, 2, 1, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 3, 1, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 1, 2, 1, 2, 2
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OFFSET
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1,8
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LINKS
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EXAMPLE
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29 -> 2 + 9 = 11 -> 1 + 1 = 2 -> persistence = 2
487 -> 4 + 8 + 7 = 19 -> 1 + 9 = 10 -> 1 + 0 = 1 -> persistence = 3
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MAPLE
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P:=proc(n) local i, k, w, ok, cont; for i from 1 by 1 to n do k:=ithprime(i); w:=0; ok:=1; if k<10 then print(0); else cont:=1; while ok=1 do while k>0 do w:=w+(k-(trunc(k/10)*10)); k:=trunc(k/10); od; if w<10 then ok:=0; print(cont); else cont:=cont+1; k:=w; w:=1; fi; od; fi; od; end: P(100);
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MATHEMATICA
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Table[Length[NestWhileList[Total[IntegerDigits[#]]&, n, #>9&]]-1, {n, Prime[ Range[100]]}] (* Harvey P. Dale, Aug 05 2014 *)
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CROSSREFS
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Cf. A031286 (additive persistence), A129985 (multiplicative persistence of primes).
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KEYWORD
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base,easy,nonn
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AUTHOR
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STATUS
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approved
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