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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.
4
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.
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
KEYWORD
nonn
AUTHOR
Artur Jasinski, Jan 29 2010
EXTENSIONS
Edited by N. J. A. Sloane, Aug 23 2020
STATUS
approved