OFFSET
1,1
COMMENTS
This sequence is the union of two sequences A145748 and A145749. See comment lines of A145749. [Farideh Firoozbakht, Nov 01 2008]
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..1000
EXAMPLE
|phi(7) - phi(6)| = |6 - 2| = |8 - 12| = |sigma(7) - sigma(6)|.
|phi(9) - phi(8)| = |6 - 4| = 2 = |13 - 15| = |sigma(9) - sigma(8)|.
MATHEMATICA
Select[ Range[ 1, 10^4 ], Abs[ DivisorSigma[ 1, # + 1 ] - DivisorSigma[ 1, # ] ] == Abs[ EulerPhi[ # + 1 ] - EulerPhi[ # ] ] & ]
PROG
(PARI) { n=0; for (m=1, 10^9, if (abs(eulerphi(m + 1) - eulerphi(m)) == abs(sigma(m + 1) - sigma(m)), write("b066198.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 05 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Joseph L. Pe, Dec 16 2001
EXTENSIONS
More terms from Jason Earls, Jun 05 2002
STATUS
approved