263820

Appears in sequences

• Unitary-sociable numbers (smallest member of each cycle).at n=5A000173
• Numbers k such that k-1, k+1, k^2+1 and k^4+1 are all prime numbers.at n=20A070156
• Irregular triangle with 4 columns which contains in each row the members of a 4-cycle under the map x->A063919(x), iteration of summing the proper-unitary divisors.at n=0A098188
• Unitary sociable numbers of order 4.at n=0A319902
• a(n) is the smallest member of the n-th purely periodic unitary sigma aliquot cycle listed in A336216.at n=20A336219