A239244 Let y be the sum of the numbers x coprime to n, with x<=n. Sequence lists n such that digits of y end in 'n'.

3, 4, 6, 80, 920, 37568, 56352, 7148453888, 7169453056, 7286124544, 7325797376, 7595232256, 8935567360, 9107655680, 13403351040

Offset

1,1

Comments

n*phi(n)/2 is of the form 'm' U 'n'.

Links

Table of n, a(n) for n=1..15.

Example

phi(920) = 352; 902*352/2 = 161920 that is '161' U '920'.

Maple

with(numtheory); P:=proc(q) local a, b, n;
for n from 1 to q do a:=n; b:=0; while a>0 do b:=b+1; a:=trunc(a/10); od;
if n=((n*phi(n)/2) mod 10^b) then print(n); fi; od; end: P(10^9);

Crossrefs

Cf. A000010, A239245.

Sequence in context: A263940 A358936 A256326 * A267943 A066466 A332511

Adjacent sequences: A239241 A239242 A239243 * A239245 A239246 A239247

Keyword

nonn,more,base

Author

Paolo P. Lava, Mar 13 2014

Extensions

a(8)-a(15) from Giovanni Resta, Mar 14 2014

Status

approved