A333913 - OEIS

A333913

Numbers k such that lambda(k) is not the sum of 3 squares, where lambda is the Carmichael lambda function (A002322).

29, 58, 61, 87, 113, 116, 122, 143, 145, 155, 157, 169, 174, 175, 183, 225, 226, 232, 235, 241, 244, 286, 290, 305, 310, 314, 317, 325, 338, 339, 348, 349, 350, 366, 371, 385, 395, 403, 427, 429, 435, 449, 450, 452, 464, 465, 470, 471, 477, 482, 488, 493, 495

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OFFSET

1,1

COMMENTS

Pollack (2011) proved that this sequence has a lower and an upper asymptotic densities, and conjectured that they do not coincide.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

Paul Pollack, Values of the Euler and Carmichael functions which are sums of three squares, Integers, Vol. 11 (2011), pp. 145-161.

EXAMPLE

1 is not a term since lambda(1) = 1 = 0^2 + 0^2 + 1^2 is the sum of 3 squares.

29 is a term since lambda(29) = 28 is not the sum of 3 squares.

MATHEMATICA