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 A351775 Value of all prime numbers p after applying the rule: sigma_n( sigma_n-1( ... sigma_3( sigma_2( sigma_1( sigma_0(p) )))...)) (from sigma_0 up to sigma_n), where sigma_k(m) is the sum of the k-th powers of the divisors of m and p is prime (the choice of the prime p is arbitrary). 0

%I #11 Feb 22 2022 14:28:56

%S 2,3,10,1134,1779741927370,

%T 18420061471485119632756156593998809036909505674991629417779936

%N Value of all prime numbers p after applying the rule: sigma_n( sigma_n-1( ... sigma_3( sigma_2( sigma_1( sigma_0(p) )))...)) (from sigma_0 up to sigma_n), where sigma_k(m) is the sum of the k-th powers of the divisors of m and p is prime (the choice of the prime p is arbitrary).

%C a(6) has 368 digits.

%F a(n) = sigma_n( a(n-1) ) for n >= 1, a(0) = 2.

%e a(0) = sigma_0(2) = 2,

%e a(1) = sigma_1( sigma_0(2) ) = 3,

%e a(2) = sigma_2( sigma_1( sigma_0(2) )) = sigma_2(3) = 10,

%e a(3) = sigma_3( sigma_2( sigma_1( sigma_0(2) ))) = sigma_3(10) = 1134.

%e ...

%t a[0] = 2; a[n_] := a[n] = DivisorSigma[n, a[n - 1]]; Table[a[n], {n, 0, 6}]

%Y Cf. A070239.

%K nonn

%O 0,1

%A _Wesley Ivan Hurt_, Feb 18 2022

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Last modified June 25 02:21 EDT 2024. Contains 373691 sequences. (Running on oeis4.)