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A291175 Numbers n such that lambda(n) = lambda(n-1) + lambda(n-2), where lambda(n) is Carmichael lambda function (A002322). 0
3, 5, 7, 11, 13, 22, 46, 371, 717, 1379, 1436, 1437, 3532, 5146, 12209, 35652, 45236, 58096, 93932, 130170, 263589, 327095, 402056, 680068, 808303, 814453, 870689, 991942, 1178628, 1670065, 1686526, 2041276, 2319102, 2324004, 3869372, 4290742, 4449280 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..37.

EXAMPLE

lambda(717) = 238 = 178 + 60 = lambda(716) + lambda(715), therefore 717 is in the sequence.

MATHEMATICA

Select[Range[10^6], CarmichaelLambda[#]==CarmichaelLambda[#-1]+CarmichaelLambda[#-2]&]

PROG

(Python)

from sympy import reduced_totient

A291175_list, a, b, c, n = [], 1, 1, 2, 3

while n < 10**6:

    if c == a + b:

        A291175_list.append(n)

        print(len(A291175_list), n)

    n += 1

    a, b, c = b, c, reduced_totient(n) # Chai Wah Wu, Aug 31 2017

CROSSREFS

Cf. A002322, A065557, A065900, A076136, A076251, A145469.

Sequence in context: A126960 A119753 A169969 * A174350 A240476 A040140

Adjacent sequences:  A291172 A291173 A291174 * A291176 A291177 A291178

KEYWORD

nonn

AUTHOR

Amiram Eldar, Aug 19 2017

STATUS

approved

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Last modified November 13 19:25 EST 2018. Contains 317149 sequences. (Running on oeis4.)