A272650 Sum_{ i in 1..p-1, j in 1..p-1, i*j mod p = 1} i*j, where p = n-th prime.

1, 5, 29, 83, 351, 519, 1291, 1747, 3357, 6553, 7501, 11839, 17219, 19263, 28199, 38583, 56049, 49043, 74771, 96133, 89059, 132087, 155209, 185653, 221741, 260983, 274803, 331913, 314355, 348943, 482091, 569587, 641707

Offset

1,2

Links

Gheorghe Coserea, Table of n, a(n) for n = 1..20000

Tsz Ho Chan, Product of a number and its multiplicative inverse, moments of L-functions and exponential sums, Integers, 16 (2016), #A2.

Maple

f:=proc(n) local p, a, b, s;
p:=ithprime(n); s:=0;
for a from 1 to p-1 do
for b from 1 to p-1 do
if (a*b mod p) = 1 then s:=s+a*b; fi;
od: od:
s; end;
[seq(f(n), n=1..40)];

Prog

(PARI) a(n) = { my(p = prime(n)); sum(i = 1, p-1, i*lift(Mod(i, p)^(-1))); }
vector(33, n, a(n)) \\ Gheorghe Coserea, May 16 2016

Crossrefs

Sequence in context: A154412 A339935 A236075 * A050409 A111937 A215850

Adjacent sequences: A272647 A272648 A272649 * A272651 A272652 A272653

Keyword

nonn

Author

N. J. A. Sloane, May 10 2016

Status

approved