A137602 a(n) is the smallest number m such that sigma(m)=n*pi(m), or 0 if no such m exists.

3, 2, 6, 38, 44, 92, 66, 174, 108, 688, 120, 954, 300, 2744, 3186, 2424, 2070, 2904, 1080, 3432, 17004, 1042810, 8976, 32232, 20916, 19260, 76908, 5284804, 98064, 281600, 31320, 4070868, 3013472, 69720, 1126380, 7272564, 52920, 316080, 336840

Offset

2,1

Comments

There is no number m such that sigma(m)=pi(m).

Links

Table of n, a(n) for n=2..40.

Example

a(29)=5284804 because sigma(5284804)=29*pi(5284804) and 5284804 is the smallest such number.

Crossrefs

Cf. A055234.

Sequence in context: A356563 A334588 A025240 * A086550 A266239 A018864

Adjacent sequences: A137599 A137600 A137601 * A137603 A137604 A137605

Keyword

easy,nonn,less

Author

Farideh Firoozbakht, Apr 11 2008

Status

approved