A341032 Numbers k such that A124440(k) is a square.

1, 2, 10, 17, 469, 646, 1542, 1601, 24939, 25090, 43690, 50925, 77577, 84002, 131087, 156817, 174755, 182106, 220974, 293930, 371307, 389130, 394290, 401573, 440819, 492886, 584326, 609301, 839590, 935685, 1727207, 1775622, 1939666, 1948705, 2235041, 2267650

Offset

1,2

Comments

Terms in common with A341031, i.e. numbers such that both A066840(k) and A124440(k) are squares, include 1, 2, 10, 17, and 25090.

Links

Daniel Suteu, Table of n, a(n) for n = 1..100

Example

a(4) = 17 is a term because A124440(17) = 100 = 10^2.

Maple

N:= 40000: # for terms <= N
G:= add(numtheory:-mobius(n)*n*x^(2*n)/((1-x^n)*(1-x^(2*n))^2), n=1..N/2):
S:= series(G, x, N+1):
A66840:= [seq(coeff(S, x, j), j=1..N)]:
f:= proc(n) n*numtheory:-phi(n)/2 - A66840[n] end proc:
f(1):= 1: f(2):= 1:
select(t -> issqr(f(t)), [$1..N]);

Crossrefs

Cf. A066840, A122440, A341031.

Sequence in context: A258974 A366508 A077247 * A082939 A074069 A069081

Adjacent sequences: A341029 A341030 A341031 * A341033 A341034 A341035

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Feb 03 2021

Extensions

More terms from Daniel Suteu, Feb 03 2021

Status

approved