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A175678 Numbers m such that arithmetic mean Ad(m) of divisors of m and arithmetic mean Ah(m) of numbers h < m such that gcd(h,m) = 1 both integer. 2
1, 6, 14, 20, 22, 30, 38, 42, 44, 46, 54, 56, 60, 62, 66, 68, 70, 78, 86, 92, 94, 96, 102, 110, 114, 116, 118, 126, 132, 134, 138, 140, 142, 150 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers m such that Ad(m) = A000203(m) / A000005(m) = A057020(m) / A057021(m) and Ah(m) = A023896(m) / A000010(m) = A026741(m) / A040001(m-1) both integer. a(n) = number 1 and even arithmetic numbers from A003601. Subsequence of A003601. Union a(n) and A175679(n+1) = A003601(n) (arithmetic numbers).

LINKS

Table of n, a(n) for n=1..34.

EXAMPLE

a(2) = 6, Ad(6) = (1+2+3+6)/4 = 3, Ah(6) = (1+5)/2 = 3, Ad(6) and Ah(6) both integer.

CROSSREFS

Sequence in context: A037177 A255217 A048747 * A173870 A101567 A123267

Adjacent sequences:  A175675 A175676 A175677 * A175679 A175680 A175681

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Aug 07 2010

STATUS

approved

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Last modified June 15 22:06 EDT 2021. Contains 345053 sequences. (Running on oeis4.)