A328761 The least integer k >= 0 for which A328578(k) = A257993(A276086(A276086(k))) = n.

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.

Links

Table of n, a(n) for n=1..52.

Index entries for sequences related to primorial base

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); };
A328578(n) = A257993(A276086(A276086(n)));
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.

Cf. A257993, A276086, A328578.

Sequence in context: A259132 A369391 A099413 * A271624 A283090 A283143

Adjacent sequences: A328758 A328759 A328760 * A328762 A328763 A328764

Keyword

nonn

Author

Antti Karttunen, Oct 27 2019

Status

approved