A340969 a(n) is the first number k with A340967(k) = n.

1, 2, 8, 12, 14, 54, 158, 159, 203, 2159, 5999, 8339, 143098, 85679, 724919, 2417594, 7415099, 44026799, 183578399, 446036579

Offset: 0

Author

J. M. Bergot and Robert Israel, Jan 31 2021

Keywords

• nonn
• more

Examples

			a(3) = 12 because A340967(12) = 3 is the first occurrence of the value 3 in A340967.
		

Crossrefs

Cf. A340967.

Programs

Maple

sopfr:= proc(n) local t;
  add(t[1]*t[2], t = ifactors(n)[2])
end proc:
f:= proc(n) local x, k;
  x:= n;
  for k from 1 do x:= n mod sopfr(x); if x <= 1 then return k fi od;
end proc:
f(1):= 0:
V:= Array(0..15): count:= 0:
for i from 1 while count < 16 do
  v:= f(i);
  if v <= 15 and V[v] = 0 then V[v]:= i; count:=count+1; fi
od:
convert(V,list);

PARI

f(n) = my(x=n,c=0,t); while(x > 1, c++; x = n % ((t=factor(x))[, 1]~*t[, 2])); c; \\ A340967
a(n) = for(k=1, oo, if(f(k) == n, return(k))); \\ Daniel Suteu, Feb 01 2021

Formula

A340967(a(n)) = n.

Extensions

a(17)-a(19) from Daniel Suteu, Feb 01 2021