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A333019 Numbers k such that both k and k + 2 are totient numbers (A002202). 6
2, 4, 6, 8, 10, 16, 18, 20, 22, 28, 30, 40, 42, 44, 46, 52, 54, 56, 58, 64, 70, 78, 80, 82, 100, 102, 104, 106, 108, 110, 126, 128, 130, 136, 138, 148, 160, 162, 164, 166, 176, 178, 190, 196, 198, 208, 210, 220, 222, 224, 226, 238, 250, 260, 262, 268, 270, 280 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

Wikipedia, Totient numbers.

EXAMPLE

2 is a term since both 2 and 4 are totient numbers.

PROG

(PARI) for(k = 1, 150, if(istotient(2*k) && istotient(2*k+2), print1(2*k, ", ")))

CROSSREFS

Cf. A000010, A002202, A005277, A063512, A083533, A333020, A333021, A333022, A333023, A333024.

Sequence in context: A338738 A226809 A161562 * A102470 A057195 A088007

Adjacent sequences:  A333016 A333017 A333018 * A333020 A333021 A333022

KEYWORD

nonn

AUTHOR

Amiram Eldar, Mar 05 2020

STATUS

approved

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Last modified May 6 09:45 EDT 2021. Contains 343580 sequences. (Running on oeis4.)