A381768 a(n) is the least positive number k for which A381763(k) = n.

1, 4, 5, 12, 604, 1338, 432, 11700, 421098, 10667760, 20109612, 68911662, 17385900, 218761404

Offset

0,2

Comments

a(n) is the least positive number k such that Omega(k+i) = Omega(k-i) for 1 <= i <= n but not for i = n + 1, where Omega = A001222.

Links

Table of n, a(n) for n=0..13.

Example

a(3) = 12 because the first appearance of 3 in A381763 is A381763(12) = 3.

Maple

W:= map(numtheory:-bigomega, [$1..10^6]):
f:= proc(n) local k;
  for k from 1 do
    if W[n-k] <> W[n+k] then return k-1 fi
  od
end proc:
f(1):= 0:
V:= Array(0..8):
for i from 0 to 10^6 - 8 do
 v:= f(i);
 if V[v] = 0 then V[0]:= i fi
od:
convert(V, list);

Crossrefs

Cf. A001222, A381763.

Sequence in context: A305335 A123102 A274077 * A028272 A003969 A326828

Adjacent sequences: A381765 A381766 A381767 * A381769 A381770 A381771

Keyword

nonn,more,changed

Author

Zak Seidov and Robert Israel, Mar 06 2025

Extensions

a(9)-a(13) from Michael S. Branicky, Jun 09 2026

Status

approved