The number n is called an apocalyptic power if 2ⁿ contains the consecutive digits 666 (in decimal).

• ...,
• 1480,
• 1482,
• 1483,
• 1485,
• 1487,
• 1488,
• 1490,
• ...

A positive integer greater than 1 that is not prime is called composite.

Composite numbers are opposite to prime numbers.

• ...,
• 1480,
• 1482,
• 1484,
• 1485,
• 1486,
• 1488,
• 1490,
• ...

The number n is deficient if the sum of all its positive divisors except itself is less than n.

Compare with perfect and abundant numbers.

• ...,
• 1479,
• 1481,
• 1483,
• 1485,
• 1486,
• 1487,
• 1489,
• ...

To build the lucky number sequence, start with natural numbers. Delete every second number, leaving 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, ... . The second number remaining is 3, so delete every third number, leaving 1, 3, 7, 9, 13, 15, 19, 21, ... . The next number remaining is 7, so delete every 7th number, leaving 1, 3, 7, 9, 13, 15, 21, ... . The next number remaining is 9, so delete every ninth number, etc.

Those numbers were lucky they weren't crossed out.

• ...,
• 1459,
• 1471,
• 1473,
• 1485,
• 1491,
• 1495,
• 1497,
• ...

A number is odd if it is not divisible by 2.

Numbers that are not odd are even. Compare with another pair -- evil and odious numbers.

• ...,
• 1479,
• 1481,
• 1483,
• 1485,
• 1487,
• 1489,
• 1491,
• ...

The number n is odious if it has an odd number of 1's in its binary expansion.

Guess what evil numbers are.

• ...,
• 1479,
• 1480,
• 1483,
• 1485,
• 1486,
• 1488,
• 1491,
• ...

If you start with n points on a line, then draw n-1 points above and between, then n-2 above and between them, and so on, you will get a triangle of points. The number of points in this triangle is a triangle number.

Compare to square, pentagonal and tetrahedral numbers.

• ...,
• 1326,
• 1378,
• 1431,
• 1485,
• 1540,
• 1596,
• 1653,
• ...