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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 (list; graph; refs; listen; history; text; internal format)
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.
LINKS
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

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Last modified March 29 08:13 EDT 2024. Contains 371265 sequences. (Running on oeis4.)