Template:Sequence of the Day for March 25

Intended for: March 25, 2013

Timetable

• First draft entered by Alonso del Arte on January 12, 2012 ✓
• Draft reviewed by Daniel Forgues on March 14, 2016 ✓
• Draft to be approved by February 25, 2013

Yesterday's SOTD * Tomorrow's SOTD

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A018834: Numbers

n

such that decimal expansion of

n 2

contains

n

as a substring.

{ 5, 6, 10, 25, 50, 60, 76, 100, ... }

Most of the terms of this sequence are rather predictable. All the powers of 10 should be in the sequence. Review of the squares of the numbers 1 to 9 suggests that there should be at least a few terms ending in 5 or 6. So it is a pleasant surprise to find 3792 as a term: its square is 14379264. The substring doesn't have to be at the end, as with multiples of 5 or 6, nor at the beginning, as with the powers of 10.