VOOZH about

URL: https://oeis.org/A058974

⇱ A058974 - OEIS

login
A058974
a(n) = 0 if n = 1 or a prime, otherwise a(n) = s + a(s) iterated until no change occurs, where s (A008472) is sum of distinct primes dividing n.
2
0, 0, 0, 2, 0, 5, 0, 2, 3, 7, 0, 5, 0, 12, 10, 2, 0, 5, 0, 7, 17, 13, 0, 5, 5, 25, 3, 12, 0, 17, 0, 2, 26, 19, 17, 5, 0, 38, 18, 7, 0, 17, 0, 13, 10, 30, 0, 5, 7, 7, 27, 25, 0, 5, 18, 12, 35, 31, 0, 17, 0, 59, 17, 2, 23, 18, 0, 19, 51, 26, 0, 5, 0, 57, 10, 38, 23, 23, 0, 7, 3, 43, 0, 17, 35, 55, 34, 13, 0
OFFSET
1,4
REFERENCES
E. N. Gilbert, An interesting property of 38, unpublished, circa 1992. Shows that 38 is the only solution of a(n) = n.
LINKS
MAPLE
f := proc(n) option remember; local i, j, k, t1, t2; if n = 1 or isprime(n) then 0 else A008472(n) + f(A008472(n)); fi; end;
MATHEMATICA
f[n_Integer] := If[n == 1 || PrimeQ[n], 0, Plus @@ First[ Transpose[ FactorInteger[n]]]]; Table[Plus @@ Drop[ FixedPointList[f, n], 1], {n, 1, 80}]
PROG
(PARI)
A008472(n) = vecsum(factor(n)[, 1]); \\ This function from M. F. Hasler, Jul 18 2015
A058974(n) = if((1==n)||isprime(n), 0, A008472(n)+A058974(A008472(n))); \\ Antti Karttunen, Oct 30 2017, after the Maple-program.
CROSSREFS
Sequence in context: A105221 A215339 A061376 * A369744 A326059 A019962
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 15 2001
EXTENSIONS
More terms from Antti Karttunen, Oct 30 2017
STATUS
approved