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A056853 n satisfying phi(n+1)-phi(n-1) = 2. +0
2
4, 6, 7, 12, 13, 15, 18, 19, 21, 30, 42, 45, 60, 63, 72, 93, 102, 108, 117, 138, 150, 165, 180, 192, 198, 213, 228, 240, 255, 270, 282, 312, 333, 348, 357, 420, 432, 453, 462, 522, 525, 570, 600, 618, 642, 660, 693, 717, 765, 810, 822, 828, 858, 882, 933, 957 (list; graph; listen)
OFFSET

1,1

EXAMPLE

phi(13+1)-phi(13-1) = 2, so 13 is a term of the sequence.

MATHEMATICA

Select[Range[10^3], EulerPhi[ # + 1] - EulerPhi[ # - 1] == 2 &]

CROSSREFS

Cf. A000010. Essentially the same as A001838.

Sequence in context: A102145 A102132 A102143 this_sequence A024566 A047506 A102136

Adjacent sequences: A056850 A056851 A056852 this_sequence A056854 A056855 A056856

KEYWORD

nonn

AUTHOR

Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Feb 12 2002

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.


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