A376223 a(n) = Sum_{i=1..q-1} d(i)^i where d(i) are the q sorted divisors of A376222(n).
5, 353, 739, 2207, 6869, 1381, 226991, 3939372150671, 24439, 68947, 389027, 493049, 12289, 148927, 35726471189, 12457, 2685629, 4330757, 1442923, 103993, 2248117, 24919, 11089577, 74820287157480518691978649, 12008999, 1225093, 205549, 104113, 21253943, 22665197
Offset: 1
Keywords
Examples
a(4) = 2207 because A376222(4) = 39 and the proper divisors of 39 are {1,3,13} with 1^1 + 3^2 + 13^3 = 2207.
Programs
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Maple
with(numtheory):nn:=900: for n from 1 to nn do: d:=divisors(n):n0:=nops(d):p:=sum(âd[k]^kâ, âkâ=1..n0-1): if isprime(p) then printf(`%d,`,p): else fi: od:
Comments