A159815 Numbers n with property that n^2 starts and ends with 49.

7, 707, 7007, 7043, 7057, 22143, 22157, 22193, 22207, 22243, 22257, 22293, 22307, 22343, 22357, 70007, 70043, 70057, 70093, 70107, 70143, 70157, 70193, 70207, 70243, 70257, 70293, 70307, 70343, 70357, 70393, 70407, 70443, 70457, 70493

Offset

1,1

Comments

Most first differences are alternatively 14 and 36.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

{7,707,7007,7043,7057,22143,22157}^2={49,499849,49098049,49603849,49801249,490312449,490932649}.

Mathematica

s7={}; Do[If[Take[IntegerDigits[n^2], 2]=={4, 9}&&PowerMod[n, 2, 100]==49, AppendTo[s7, n]], {n, 7, 300000}]; s7
se49Q[n_]:=Module[{id=IntegerDigits[n^2]}, Take[id, 2]==Take[id, -2] == {4, 9}]; Select[Range[5, 71000], se49Q] (* Harvey P. Dale, Apr 22 2016 *)

Crossrefs

A159775 Numbers n with property that n^2 starts and ends with 81. A159754 Numbers n with property that n^2 ends with 81. A159254 Numbers n with property that n^2 ends with 49. A111445 n-th row contains first n numbers whose squares end in n^2.

Sequence in context: A186160 A129291 A229149 * A070746 A068004 A098110

Adjacent sequences: A159812 A159813 A159814 * A159816 A159817 A159818

Keyword

base,nonn

Author

Zak Seidov, Apr 22 2009

Status

approved