OFFSET
1,1
COMMENTS
Numbers k such that k and k+1 are both terms of A360906.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1000
EXAMPLE
MATHEMATICA
q[n_] := Module[{e = FactorInteger[n][[;; , 2]]}, Times @@ (Min[#, 3] & /@ (e + 1)) == Times @@ (Max[#, 1] & /@ (e - 1))]; q[1] = True; seq[kmax_] := Module[{s = {}, k = 1, q1 = q[1], q2}, Do[q2 = q[k]; If[q1 && q2, AppendTo[s, k-1]]; q1 = q2, {k, 2, kmax}]; s]; seq[2*10^5]
PROG
(PARI) is(k) = {my(e = factor(k)[, 2]); prod(i = 1, #e, min(e[i] + 1, 3)) == prod(i = 1, #e, max(e[i] - 1, 1)); }
lista(kmax) = {my(is1 = is(1), i2); for(k=2, kmax, is2 = is(k); if(is1 && is2, print1(k-1, ", ")); is1 = is2); }
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Feb 25 2023
STATUS
approved