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A100879
a(n) = n^sigma(n).
4
1, 8, 81, 16384, 15625, 2176782336, 5764801, 35184372088832, 2541865828329, 1000000000000000000, 3138428376721, 1648446623609512543951043690496, 3937376385699289, 3214199700417740936751087616
OFFSET
1,2
FORMULA
a(n) = n^A000203(n). - Michel Marcus, Mar 17 2018
Sum_{n>=1} 1/a(n) = A192265. - Amiram Eldar, Nov 15 2020
EXAMPLE
a(1) = 1^1 = 1;
a(2) = 2^(1+2) = 8;
a(3) = 3^(1+3) = 81;
a(4) = 4^(1+2+4) = 16384.
MAPLE
with(numtheory): seq(n^add(d, d=divisors(n)), n=1..17); # C. Ronaldo, Jan 19 2005
MATHEMATICA
Table[n^DivisorSigma[1, n], {n, 20}] (* Harvey P. Dale, Oct 05 2011 *)
PROG
(PARI) a(n)=n^sigma(n) \\ Charles R Greathouse IV, Aug 25 2014
CROSSREFS
Sequence in context: A100399 A022504 A104126 * A080811 A249898 A073699
KEYWORD
easy,nonn
AUTHOR
Odimar Fabeny, Jan 09 2005
EXTENSIONS
More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 19 2005
STATUS
approved