A201123 Differences between odd powers of 7 and the next smaller square.

3, 19, 166, 894, 5703, 12654, 620046, 4235622, 24518766, 133763479, 575536407, 7275224659, 63521178243, 36407018199, 1783943891751, 12048048160062, 62797942092807, 615169213046419, 4293026969512678, 29406470217788179, 174254081653289398, 2627356192258967382

Offset

1,1

Links

Hugo Pfoertner, Table of n, a(n) for n = 1..500

Formula

a(n) = 7^(2*n-1) - floor(sqrt(7^(2*n-1)))^2.

Example

a(1) = 7^1 - 2^2 = 3;
a(2) = 7^3 - 18^2 = 343 - 324 = 19;
a(3) = 7^5 - 129^2 = 16807 - 16641 = 166.

Mathematica

Table[7^(2 n - 1) - Floor[Sqrt[7^(2 n - 1)]]^2, {n, 30}] (* Wesley Ivan Hurt, Mar 06 2014 *)

Crossrefs

Cf. A051218.

Sequence in context: A183069 A256710 A215093 * A260700 A105624 A238640

Adjacent sequences: A201120 A201121 A201122 * A201124 A201125 A201126

Keyword

nonn

Author

Hugo Pfoertner, Nov 27 2011

Status

approved