OFFSET
0,1
COMMENTS
x = a(n) and y = A002042(n) satisfy the Lebesgue-Ramanujan-Nagell equation x^2 + 3^(6*n+1) = 4*y^3 (see Theorem 2.1 in Chakraborty, Hoque and Sharma).
LINKS
K. Chakraborty, A. Hoque, R. Sharma, Complete solutions of certain Lebesgue-Ramanujan-Nagell type equations, arXiv:1812.11874 [math.NT], 2018.
Index entries for linear recurrences with constant coefficients, signature (27).
FORMULA
EXAMPLE
For a(0) = 37 and A002042(0) = 7, 37^2 + 3 = 1372 = 4*7^3.
MAPLE
a:=n->37*27^n: seq(a(n), n=0..20);
MATHEMATICA
37*27^Range[0, 20]
PROG
(GAP) List([0..20], n->37*27^n);
(Magma) [37*27^n: n in [0..20]];
(PARI) a(n) = 37*27^n;
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Stefano Spezia, Feb 18 2019
STATUS
approved