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 A107450 Additive persistence of the prime numbers. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,8 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 EXAMPLE 29 -> 2 + 9 = 11 -> 1 + 1 = 2 -> persistence = 2 487 -> 4 + 8 + 7 = 19 -> 1 + 9 = 10 -> 1 + 0 = 1 -> persistence = 3 MAPLE 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); MATHEMATICA Table[Length[NestWhileList[Total[IntegerDigits[#]]&, n, #>9&]]-1, {n, Prime[ Range[100]]}] (* Harvey P. Dale, Aug 05 2014 *) CROSSREFS Cf. A031286 (additive persistence), A129985 (multiplicative persistence of primes). Sequence in context: A188512 A081129 A022934 * A341765 A104248 A358359 Adjacent sequences: A107447 A107448 A107449 * A107451 A107452 A107453 KEYWORD base,easy,nonn AUTHOR Paolo P. Lava and Giorgio Balzarotti, Jun 22 2007 STATUS approved

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Last modified April 18 22:18 EDT 2024. Contains 371782 sequences. (Running on oeis4.)