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A133909
Least odd number m such that binomial(n+m,m) mod m = 1.
0
3, 3, 5, 5, 7, 7, 9, 9, 3, 3, 3, 13, 17, 17, 17, 17, 19, 3, 3, 3, 23, 23, 25, 25, 5, 5, 3, 3, 3, 31, 37, 37, 37, 37, 37, 3, 3, 3, 41, 41, 43, 43, 47, 47, 3, 3, 3, 49, 7, 5, 5, 5, 5, 3, 3, 3, 9, 9, 9, 61, 67, 67, 3, 3, 3, 67, 71, 71, 71, 71, 73, 3, 3, 3, 5, 5, 5, 5, 5, 83, 3, 3, 3, 89, 89, 89, 9, 9
OFFSET
1,1
EXAMPLE
a(3)=5, since binomial(3+5,5) mod 5 = 56 mod 5 = 1 and 5 is the minimal odd number with this property.
a(8)=9 because of binomial(8+9,9)=24310=2701*9+1, but binomial(8+k,k) mod k<>1 for all odd numbers <9.
KEYWORD
nonn
AUTHOR
Hieronymus Fischer, Oct 20 2007
STATUS
approved