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A328761
The least integer k >= 0 for which A328578(k) = A257993(A276086(A276086(k))) = n.
3
1, 0, 2, 4, 10, 20, 28, 82, 116, 148, 208, 418, 838, 1048, 1466, 1858, 2276, 4612, 9028, 11546, 16162, 18478, 23098, 27688, 30028, 90086, 147838, 180178, 240232, 297988, 330328, 390358, 450238, 480478, 1021016, 2039728, 3033028, 3573566, 4594558, 5105098, 6606598, 7147136, 8168152, 8678668, 9699688, 29099062, 48498238, 58198138, 77597516, 96996896, 106696588, 126095968
OFFSET
1,3
COMMENTS
The sequence seems to be monotonic from the second term onward. If this holds, then this sequence (after the initial 1) gives also the positions of records in A328578. See also the scatterplot of A328578.
PROG
(PARI)
A257993(n) = { for(i=1, oo, if(n%prime(i), return(i))); }
A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A328761(n) = for(k=0, oo, if(A328578(k)==n, return(k)));
(PARI)
A328761list(up_to) = { my(v=vector(up_to), k); for(n=0, oo, k=A328578(n); if(k>#v, return(v)); if(!v[k], v[k] = n; print("Found ", k, " at n=", n)); if(k>=#v, return(v))); };
v328761 = A328761list(52);
A328761(n) = if(2==n, 0, v328761[n]);
CROSSREFS
Column 1 of A328631.
Sequence in context: A259132 A369391 A099413 * A271624 A283090 A283143
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 27 2019
STATUS
approved