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A137733 Numbers n such that sigma(2 phi(n)) = 2 sigma(n). 0
2318, 2806, 5734, 5937, 7198, 8097, 10126, 11295, 11818, 13054, 17324, 20374, 21838, 22947, 27694, 29145, 32086, 33826, 35074, 38997, 42334, 42458, 43798, 46726, 54825, 56974, 58438, 61366, 66202, 68686, 71614, 86762, 86924, 87435 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

LINKS

Jean-Marie De Koninck and Florian Luca, Positive Integers n Such That sigma(phi(n))=sigma(n), Journal of Integer Sequences, Paper No. 08.1.5, 2008.

EXAMPLE

a(1) = 2318, because this is the smallest integer such that sigma(2 phi(n)) = 2 sigma(n).

CROSSREFS

Sequence in context: A132214 A133538 A075668 * A205636 A119735 A115933

Adjacent sequences:  A137730 A137731 A137732 * A137734 A137735 A137736

KEYWORD

nonn

AUTHOR

Jeffrey Shallit (shallit(AT)graceland.uwaterloo.ca), Feb 09 2008; definition corrected Feb 09 2008

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Last modified February 14 14:07 EST 2012. Contains 205623 sequences.