A238712 Numbers in which squares may end (in base 10).

0, 1, 4, 5, 6, 9, 16, 21, 24, 25, 29, 36, 41, 44, 49, 56, 61, 64, 69, 76, 81, 84, 89, 96, 100, 104, 116, 121, 124, 129, 136, 144, 156, 161, 164, 169, 176, 184, 196, 201, 204, 209, 216, 224, 225, 236, 241, 244, 249, 256, 264, 276, 281, 284, 289, 296, 304

Offset

1,3

Comments

The union of "squares mod 10" (= the first 6 terms) and "squares mod 100" (A010461) and "squares mod 1000" (A122986) etc.

The number of terms < 10^k beginning with k=0: 1, 6, 24, 165, 1101, 9306, 79620, 753462, 7198791, 70919559, ... - Robert G. Wilson v, Sep 04 2014

Links

Derek Orr, Table of n, a(n) for n = 1..9306

Formula

If n is present so is n^2. - Robert G. Wilson v, Sep 04 2014

Example

6 is in the sequence because 4^2 = 16 ends in the digit 6.
7 is not in the sequence because no square can end with the digit 7.

Mathematica

mx = 3; t = Union@ Table[ Mod[n^2, 10^mx], {n, 10^mx/2}]; t = Union@ Flatten@ Table[ Mod[t, 10^m], {m, mx}] (* Robert G. Wilson v, Sep 04 2014 *)

Prog

(PARI) a=[]; for(m=1, 3, a=setunion(a, Set(vector(10^m, n, n^2)%10^m))); a

Crossrefs

Cf. A161355, A246422, A246448 (Complement).

Sequence in context: A020669 A091730 A058076 * A033819 A058782 A115762

Adjacent sequences: A238709 A238710 A238711 * A238713 A238714 A238715

Keyword

nonn,base

Author

M. F. Hasler, Mar 03 2014

Status

approved