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A372009
Indices k such that A124652(k) is prime.
3
2, 3, 5, 11, 12, 20, 24, 28, 29, 33, 42, 43, 53, 58, 67, 78, 93, 98, 104, 105, 109, 112, 118, 125, 126, 137, 141, 145, 146, 162, 174, 182, 185, 187, 188, 195, 200, 223, 224, 231, 232, 239, 246, 249, 252, 255, 259, 264, 271, 275, 283, 286, 287, 296, 298, 300, 326
OFFSET
1,1
COMMENTS
Analogous to A111238, a sequence which instead pertains to A109890.
LINKS
Michael De Vlieger, Log log scatterplot of A124652(n), n = 1..25000, showing primes in red.
FORMULA
Proper subset of A372028.
EXAMPLE
Let b(x) = A124652(x).
Table of first terms.
n a(n) b(a(n))
-----------------
1 2 2
2 3 3
3 5 5
4 11 11
5 12 7
6 20 31
7 24 13
8 28 19
9 29 17
10 33 37
11 42 29
12 43 41
...
MATHEMATICA
nn = 300; c[_] := False;
rad[x_] := rad[x] = Times @@ FactorInteger[x][[All, 1]];
f[x_] := Select[Range[x], Divisible[x, rad[#]] &];
Array[Set[{a[#], c[#]}, {#, True}] &, 2]; s = a[1] + a[2];
{2}~Join~Reap[Do[r = f[s]; k = SelectFirst[r, ! c[#] &];
If[PrimeQ[k], Sow[i]]; c[k] = True;
s += k, {i, 3, nn}] ][[-1, 1]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael De Vlieger, Apr 29 2024
STATUS
approved