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A015699
Number of 5-tuples of different integers from [ 2,n ] with no common factors among pairs.
0
0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 6, 33, 35, 38, 48, 157, 162, 400, 425, 478, 511, 1076, 1111, 1562, 1673, 2058, 2183, 3880, 3915, 6449, 7100, 7810, 8281, 9361, 9578, 14767, 15608, 17032, 17578, 25860, 26154, 37110, 38842, 40837, 42873, 58971, 60071
OFFSET
2,10
MAPLE
for n from 2 to 50 do s:=[0, 0]: t:=[seq(2*i-1, i=2..floor((n+1)/2))]:for n1 from 2 to n do i:= n1 mod 2 +1: for n2 in t do if(n1<>n2 and igcd(n1, n2)=1) then for n3 in t do if(n1<>n3 and n2<>n3 and igcd(n1, n3)=1 and igcd(n2, n3)=1) then for n4 in t do if(n1<>n4 and n2<>n4 and n3<>n4 and igcd(n1, n4)=1 and igcd(n2, n4)=1 and igcd(n3, n4)=1) then for n5 in t do if(n1<>n5 and n2<>n5 and n3<>n5 and n4<>n5 and igcd(n1, n5)=1 and igcd(n2, n5)=1 and igcd(n3, n5)=1 and igcd(n4, n5)=1) then s[i]:=s[i]+1 fi od fi od fi od fi od od: printf("%d, ", s[1]/4!+s[2]/5!) od: # C. Ronaldo
CROSSREFS
Sequence in context: A074002 A359741 A140959 * A244416 A165827 A256136
KEYWORD
nonn
STATUS
approved