OFFSET
0,1
COMMENTS
Conjecture: A001221(a(n)) = n+1, for n >= 2. - Daniel Suteu, May 08 2024
EXAMPLE
a(0) = 6 as 6 = 2 * 3 while sopfr(6) = 5, which shares 0 distinct prime factors with 6.
a(1) = 4 as 4 = 2 * 2 while sopfr(4) = 4 = 2 * 2, which shares 1 distinct prime factor, 2, with 4.
a(2) = 30 as 30 = 2 * 3 * 5 while sopfr(30) = 10 = 2 * 5, which shares 2 distinct prime factors, 2 and 5, with 30.
a(3) = 1530 as 1530 = 2 * 3^2 * 5 * 17 while sopfr(1530) = 30 = 2 * 3 * 5, which shares 3 distinct primes factors, 2, 3 and 5, with 1530.
a(4) = 40530 as 40530 = 2 * 3 * 5 * 7 * 193 while sopfr(40530) = 210 = 2 * 3 * 5 * 7, which shares 4 distinct prime factors, 2, 3, 5 and 7, with 40530.
a(5) = 37838430 as 37838430 = 2 * 3^2 * 5 * 7 * 17 * 3533 while sopfr(37838430) = 3570 = 2 * 3 * 5 * 7 * 17, which shares 5 distinct prime factors, 2, 3, 5, 7 and 17, with 37838430.
a(6) = 900569670 as 900569670 = 2 * 3 * 5 * 7 * 11 * 13 * 29989 while sopfr(900569670) = 30030 = 2 * 3 * 5 * 7 * 11 * 13, which shares 6 distinct prime factors, 2, 3, 5, 7, 11 and 13, with 900569670.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Scott R. Shannon, May 05 2024
EXTENSIONS
a(7) from Daniel Suteu, May 08 2024
STATUS
approved