A144715 A144325(n) + A144313(n) + A144315(n).

275, 431, 587, 1115, 1271, 2309, 2891, 3203, 3725, 4421, 4787, 5453, 6017, 6257, 6599, 6797, 7295, 7841, 8507, 8735, 8975, 9233, 9557, 9983, 10733, 11327, 11939, 12875, 13031, 13439, 14285, 15113, 15383, 15665, 16307, 17129, 17849, 18461

Offset: 1

Author

Reikku Kulon, Sep 19 2008

Keywords

• easy
• nonn

Comments

All terms are congruent to 5 modulo 6: A144325(n) and A144313(n) are each congruent to 5 and A144315(n) is congruent to 1.

None of the given terms have more than three distinct prime factors and most have only two. Several are primes.

The multiples of five are all fifth figurate numbers corresponding to polygons having a number of sides k = floor(a(n) / 10) + 2. 3725 = 5 * 5 * 149 is also the 50th pentagonal number. The rest are not figurates, except for 15113 = 7 * 17 * 127, which is the seventeenth 113-figurate number.

Crossrefs

Cf. A144325, A144313, A144315, A000326