A228081 - OEIS

A228081

a(n) = 64^n + 1.

2, 65, 4097, 262145, 16777217, 1073741825, 68719476737, 4398046511105, 281474976710657, 18014398509481985, 1152921504606846977, 73786976294838206465, 4722366482869645213697, 302231454903657293676545, 19342813113834066795298817, 1237940039285380274899124225

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OFFSET

0,1

COMMENTS

These numbers can be written as the sum of two relatively prime squares and also as the sum of two relatively prime cubes (i.e., 2^(6*n) + 1 = (2^(3*n))^2 + 1^2 = (2^(2*n))^3 + 1^3).

LINKS

Arkadiusz Wesolowski, Table of n, a(n) for n = 0..100

Index entries for sequences related to sums of cubes

Index entries for sequences related to sums of squares

Index entries for linear recurrences with constant coefficients, signature (65,-64).

FORMULA

a(n) = 64*a(n-1) - 63.

a(n) = A089357(n) + 1 = 2^A008588(n) + 1.

G.f.: (2 - 65*x)/((1 - x)*(1 - 64*x)).

E.g.f.: e^x + e^(64*x).

EXAMPLE

a(2) = 64^2 + 1 = 4097.