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A356451
Numbers k such that 4*k^2 is in A014567.
5
1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 36, 37, 38, 40, 41, 43, 44, 45, 46, 47, 48, 50, 51, 52, 53, 54, 55, 58, 59, 60, 61, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 79, 80, 81, 82, 83
OFFSET
1,2
COMMENTS
Numbers k such that k and sigma(4*k^2) are coprime, sigma = A000203.
LINKS
Jianing Song, Table of n, a(n) for n = 1..7127 (all terms <= 10000)
FORMULA
a(n) = A356448(n)/2.
EXAMPLE
12 is a term since 12 and sigma(4*12^2) = 1651 are coprime.
PROG
(PARI) isA356450(n) = gcd(n, sigma(4*n^2))==1
CROSSREFS
Cf. A014567, A000203, A356382, A356448, A356449, A356454 (complement).
Sequence in context: A004726 A298747 A327105 * A129618 A349536 A038673
KEYWORD
nonn,easy
AUTHOR
Jianing Song, Aug 07 2022
STATUS
approved