A121236 - OEIS

A121236

Primes of the form A001228(n) + 1 and A001228(n) - 1 where A001228 = orders of sporadic simple groups.

7919, 604801, 10200959, 44351999, 44352001, 50232961, 244823041, 460815505919, 64561751654399, 4089470473293004801, 4157776806543360001, 86775571046077562879

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OFFSET

1,1

COMMENTS

This is not an arbitrary thing to do, as in some cases the sporadic group has an order depending on a specific power, as with A001228(1) + 1 = 7921 = 89^2 and A001228(3) + 1 = 175561 = 419^2. The largest integer to check is 1 + the order of the monster group, which is the semiprime 808017424794512875886459904961710757005754368000000001 = 18250906752127213 * 44272727693397225537389001926419074277.

LINKS

Table of n, a(n) for n=1..12.

FORMULA

({A001228(n) + 1} UNION {A001228(n) - 1}) INTERSECTION A000040.

EXAMPLE

a(1) = 7919 = A001228(1) - 1.

a(2) = 604801 = A001228(5) + 1.

a(3) = 10200959 = A001228(6) - 1.

a(4) = 44351999 = A001228(7) - 1.

a(5) = 44352001 = A001228(7) + 1.

a(6) = 50232961 = A001228(8) + 1.

a(7) = 244823041 = A001228(9) + 1.