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A080182 a(1) = 1, a(n+1) = a(n) + gpf(Sum_{i=1..n} a(i)), where gpf=A006530 (greatest prime factor). 3
1, 2, 5, 7, 12, 15, 22, 24, 35, 76, 275, 354, 377, 618, 2441, 2482, 5855, 18456, 20845, 46796, 47605, 53966, 54705, 182192, 182355, 211856, 213153, 214712, 216985, 1693212, 1694413, 1713714, 1716967, 1717074, 11728681, 11729202, 11738033, 11752860, 12041999, 12180558 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n+1) = a(n) + gpf(A080183(n)) for n > 0.
MATHEMATICA
gpf[n_] := FactorInteger[n][[-1, 1]];
a[n_] := a[n] = If[n == 1, 1, a[n-1] + gpf[Sum[a[i], {i, 1, n-1}]]];
Array[a, 40] (* Jean-François Alcover, Dec 17 2021 *)
PROG
(PARI) \\ here b(n) is A006530(n).
b(n)={if(n==1, 1, my(f=factor(n)[, 1]); f[#f])}
seq(n)={my(a=vector(n), s=1); a[1] = 1; for(n=2, n, a[n] = a[n-1] + b(s); s += a[n]); a} \\ Andrew Howroyd, Apr 20 2021
CROSSREFS
Cf. A006530 (gpf), A080180, A080183.
Sequence in context: A349744 A129232 A088822 * A001318 A024702 A343944
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Feb 05 2003
EXTENSIONS
Terms a(30) and beyond from Andrew Howroyd, Apr 20 2021
STATUS
approved

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Last modified June 12 14:26 EDT 2024. Contains 373331 sequences. (Running on oeis4.)