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, 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

Links

Table of n, a(n) for n=2..48.

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

Adjacent sequences: A015696 A015697 A015698 * A015700 A015701 A015702

Keyword

nonn

Author

Olivier Gérard

Status

approved