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A258974
a(n) = 1 + sigma(n)^2.
3
2, 10, 17, 50, 37, 145, 65, 226, 170, 325, 145, 785, 197, 577, 577, 962, 325, 1522, 401, 1765, 1025, 1297, 577, 3601, 962, 1765, 1601, 3137, 901, 5185, 1025, 3970, 2305, 2917, 2305, 8282, 1445, 3601, 3137, 8101, 1765, 9217, 1937, 7057, 6085, 5185, 2305
OFFSET
1,1
FORMULA
a(n) = 1 + A000203(n)^2.
a(n) = 1 + A072861(n). - Omar E. Pol, Jun 19 2015
a(n) = A002522(A000203(n)). - Michel Marcus, Jun 25 2015
MAPLE
with(numtheory): A258974:=n->1+sigma(n)^2: seq(A258974(n), n=1..100); # Wesley Ivan Hurt, Jul 09 2015
MATHEMATICA
Table[1 + DivisorSigma[1, n]^2, {n, 10000}]
Table[Cyclotomic[4, DivisorSigma[1, n]], {n, 10000}]
PROG
(Magma) [(1 + DivisorSigma(1, n)^2): n in [1..50]]; // Vincenzo Librandi, Jun 16 2015
(PARI) a(n)=sigma(n)^2+1 \\ Charles R Greathouse IV, Jun 18 2015
CROSSREFS
Cf. A000203 (sum of divisors of n).
Cf. A258976 (indices of primes in this sequence), A258977 (corresponding primes).
Sequence in context: A304805 A214086 A127492 * A366508 A077247 A341032
KEYWORD
easy,nonn
AUTHOR
Robert Price, Jun 15 2015
STATUS
approved