A239244 Integers m such that the sum of the integers x <= m coprime to m ends with digits of m.

3, 4, 6, 80, 920, 37568, 56352, 7148453888, 7169453056, 7286124544, 7325797376, 7595232256, 8935567360, 9107655680, 13403351040, 327148445696, 334938038272, 381673578496, 490722668544, 502407057408, 572510367744, 700408935710720, 90431107185349337546752

Offset

1,1

Comments

Equivalently, m*phi(m)/2 ends with digits of m.

Links

Max Alekseyev, Table of n, a(n) for n = 1..59

Example

For m = 920, we have phi(920) = 352 and 902*352/2 = 161920 ends with digits of 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: A358936 A387197 A256326 * A267943 A066466 A332511

Adjacent sequences: A239241 A239242 A239243 * A239245 A239246 A239247

Keyword

nonn,base

Author

Paolo P. Lava, Mar 13 2014

Extensions

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

Edited and terms a(16) onward added by Max Alekseyev, Dec 13 2024

Status

approved