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A230006 Numbers n such that sigma(n) + phi(n) = reversal(n) + 1. 5
1, 37, 225, 397, 11112722, 1309286244182 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

If p=4*10^m-3 is prime then p is in the sequence.

a(7) > 10^13. - Giovanni Resta, Feb 08 2014

LINKS

Table of n, a(n) for n=1..6.

EXAMPLE

sigma(37)+phi(37)=38+36=73+1=reversal(37)+1.

MATHEMATICA

r[n_] := FromDigits[Reverse[IntegerDigits[n]]]; Do[If[DivisorSigma[1, n] + EulerPhi[n] == r[n]+1, Print[n]], {n, 1000000000}]

CROSSREFS

Cf. A000010, A000203, A004086, A230004, A230005.

Sequence in context: A327033 A052166 A142010 * A284987 A133958 A088544

Adjacent sequences:  A230003 A230004 A230005 * A230007 A230008 A230009

KEYWORD

nonn,base,more

AUTHOR

Farideh Firoozbakht, Dec 02 2013

EXTENSIONS

a(6) from Giovanni Resta, Feb 06 2014

STATUS

approved

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Last modified December 5 15:06 EST 2021. Contains 349557 sequences. (Running on oeis4.)