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A053229 Numbers n for which second differences of sigma(n) are negative. 3
1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 104, 105, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125, 127, 129 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..66.

MAPLE

with(numtheory): seq(`if`(sigma(i+2)-sigma(i+1)<(sigma(i+1)-sigma(i)), i, print( )), i=1..133);

CROSSREFS

Cf. A000203, A053223, A053228.

Sequence in context: A064679 A081874 A165747 * A157142 A247328 A004273

Adjacent sequences:  A053226 A053227 A053228 * A053230 A053231 A053232

KEYWORD

nonn

AUTHOR

Asher Auel (asher.auel(AT)reed.edu) Dec 10, 2000

STATUS

approved

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Last modified March 29 15:31 EDT 2017. Contains 284273 sequences.