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A247137
Numbers for which the root mean square of nontrivial divisors is an integer and which are not a square of prime numbers.
2
119, 161, 343, 369, 527, 711, 721, 833, 959, 1081, 1127, 1241, 1695, 1767, 2047, 3281, 3335, 3553, 3713, 4207, 4633, 4681, 5047, 5215, 6713, 6887, 7327, 7775, 9641, 12319, 14031, 16617, 16999, 18473, 19199, 22145, 27009, 27913, 29449, 31679, 32239, 32599, 37241, 44801, 45385, 47865, 47959, 50279, 52319, 56033
OFFSET
1,1
COMMENTS
That's the numbers which are in A247136 and not in A001248.
LINKS
Daniel Lignon and Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (terms up to 148 from Lignon)
PROG
(PARI) integralRMS(v)=my(t=norml2(v)/#v); denominator(t)==1 && issquare(t)
is(n)=my(d=divisors(n)); #d>3 && integralRMS(d[2..#d-1]) \\ Charles R Greathouse IV, Nov 20 2014
CROSSREFS
Cf. A247136 (Numbers for which the root mean square of nontrivial divisors is an integer).
Sequence in context: A135716 A026049 A273179 * A134603 A134604 A255580
KEYWORD
nonn
AUTHOR
Daniel Lignon, Nov 20 2014
STATUS
approved