A343242 Nonprime numbers k such that A054008(k) = A054024(k).

1, 20, 196, 368, 650, 672, 780, 836, 1888, 2352, 3192, 11096, 17816, 20496, 30240, 51060, 84660, 130304, 979992, 1848964, 2291936, 3767100, 4526272, 8353792, 15126992, 15287976, 23569920, 33468416, 45532800, 74899952, 381236216, 623799776, 712023296, 1845991216

Offset

1,2

Comments

If p is an odd prime then A054008(p) = A054024(p) = 2. Therefore, this sequence is restricted to nonprime numbers.

Links

Table of n, a(n) for n=1..34.

Example

20 is a term since it is a nonprime number and A054008(20) = A054024(20) = 2.

Mathematica

Select[Range[10^6], !PrimeQ[#] && Mod[#, DivisorSigma[0, #]] == Mod[DivisorSigma[1, #], #] &]

Crossrefs

Cf. A000005, A000203, A054008, A054024.

Subsequences: A047728, A245782.

Sequence in context: A232224 A338778 A375803 * A219935 A191299 A027716

Adjacent sequences: A343239 A343240 A343241 * A343243 A343244 A343245

Keyword

nonn

Author

Amiram Eldar, Apr 08 2021

Status

approved