A081501 In the following triangle the n-th row begins with n and contains n-1 smallest numbers coprime to n and greater than n. Sequence gives the row sums.

1, 5, 12, 25, 35, 73, 70, 113, 129, 201, 176, 325, 247, 393, 408, 481, 425, 757, 532, 851, 789, 969, 782, 1369, 985, 1353, 1236, 1633, 1247, 2479, 1426, 1985, 1931, 2313, 2064, 3133, 2035, 2889, 2691, 3501, 2501, 4709, 2752, 3969, 3839, 4233, 3290, 5617, 3745

Offset

1,2

Comments

1

2 3

3 4 5

4 5 7 9

5 6 7 8 9

6 7 11 13 17 19

7 8 9 10 11 12 13

8 9 11 13 15 17 19 21

For a prime p, a(p) = p*( 3p- 1)/2.

Links

Table of n, a(n) for n=1..49.

Prog

(PARI) for(k=1, 100, t=0; s=k+1; i=k+1; while(i<k+(k), if(gcd(s, k)==1, t+=s; i++); s++); print1(t+k, ", ")) - Lambert Herrgesell (zero815(AT)googlemail.com), Mar 14 2006

Crossrefs

Cf. A081500.

Sequence in context: A272194 A169699 A109624 * A355947 A274629 A082019

Adjacent sequences: A081498 A081499 A081500 * A081502 A081503 A081504

Keyword

nonn

Author

Amarnath Murthy, Mar 25 2003

Extensions

More terms from Lambert Herrgesell (zero815(AT)googlemail.com), Mar 14 2006

Status

approved