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A113929 Numbers n such that sigma(n) and phi(n) are both palindromes. 0
1, 2, 3, 4, 5, 7, 2881, 15456, 20930, 26461, 26772, 43262, 135536, 271171, 2118161, 2362081, 2545951, 2779321, 4236322, 6354483, 12936656, 28666681, 221782512, 253676851, 259202401, 259828451, 276025121, 276949721, 437593059, 472911836 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

phi(n)=A000010(n) is the Euler totient function, while sigma(n)=A000203(n) is the sum of divisors of n

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

sigma(2118161)=2122212 and phi(2118161)=2114112.

CROSSREFS

Cf. A000010, A000203.

Sequence in context: A028986 A327324 A063948 * A220394 A082351 A122319

Adjacent sequences:  A113926 A113927 A113928 * A113930 A113931 A113932

KEYWORD

base,nonn

AUTHOR

Giovanni Resta, Jan 30 2006

EXTENSIONS

a(21)-a(31) from Donovan Johnson, Dec 14 2009

STATUS

approved

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Last modified June 21 15:37 EDT 2021. Contains 345364 sequences. (Running on oeis4.)