A172248 Numbers n such that there do not exist two ways of writing n = a+b with a<=b, gcd(n,a,b)=1, and the same value of N(a,b,n) = product of distinct prime divisors of a*b*n.

2, 3, 4, 5, 6, 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 26, 27, 28, 30, 32, 33, 34, 36, 38, 42, 44, 45, 46, 48, 50, 51, 52, 54, 56, 60, 62, 64, 66, 68, 69, 70, 72, 74, 75, 76, 78, 80, 81, 82, 84, 86, 87, 88, 90, 92, 94, 96, 98, 100, 102, 104, 105, 106, 108, 110, 112, 114, 116, 118

Offset

2,1

Comments

Number of partitions n as sum a + b such that a<=b and gcd(a,b,n)=1 is given in A023022

Number of partitions having distinct values of N(a,b,n) is given in A172245

Number of partitions having the same values of N(a,b,n) is given in A172247

Numbers n for which all partitions have different value of N(a,b,n) are given in A172248.

Links

Table of n, a(n) for n=2..70.

Example

7 doesn't belong to this sequence because for 7 we have two partitions 7=1+6 and 7=3+4 with that same values of N(a,b,n) respectively 1*2*3*7=42 and 2*3*7=42.

Crossrefs

Cf. A023022, A172245, A172246, A172247.

Sequence in context: A172121 A094222 A164043 * A082415 A005236 A051250

Adjacent sequences: A172245 A172246 A172247 * A172249 A172250 A172251

Keyword

nonn

Author

Artur Jasinski, Jan 29 2010

Extensions

Edited by N. J. A. Sloane, Aug 23 2020

Status

approved