A124275 Terms of A123856 that are not terms of A124273.

2, 5, 181

Offset: 1

Author

Alexander Adamchuk, Oct 23 2006

Keywords

• bref
• hard
• more
• nonn

Comments

Primes that divide A123855(p-1) = Sum_{j=1..p-1} Sum_{i=1..p-1} prime(i)^j but not A124271(p) = Sum_{i=1..p} (prime(i)^p - 1)/(prime(i) - 1).

The next term if it exists is greater than 1000.

The next term A124275(4), if it exists, is larger than 25000. (Checked by calculating sequences A123856 and A124273 to 1200 terms.) - M. F. Hasler, Nov 10 2006

Examples

			A123856(n) begins {2, 3, 5, 7, 13, 17, 19, 31, 47, 59, 61, 71, 101, 103, 107, 109, 137, 149, 151, 157, 167, 181, 197, ...}.
A124273(n) begins {3, 7, 13, 17, 19, 31, 47, 59, 61, 71, 101, 103, 107, 109, 137, 149, 151, 157, 167, 197, ...}.
Thus a(1) = 2, a(2) = 5, a(3) = 181.
		

Crossrefs

Cf. A123855, A123856, A124271, A124273.

Programs

Maple

A124275:=proc(n) option remember; local i1,i2; i1:=1:i2:=1: # find index i1 such that A123856[i1] is > A124275[n-1]; # then continue until A124273 "jumped over" the term A123856[i1] # while n>1 and A123856(i1) <= procname(n-1) or A123856(i1) = A124273(i2) do i1:=i1+1: # find index i2 such that A124273[i2] is >= A123856(i1) # while A124273(i2) < A123856(i1) do i2:=i2+1: od: od: A123856(i1) end; # M. F. Hasler, Nov 10 2006