## zondag 19 februari 2017

### R1001

$$2^{1001}·7·11·13$$

### Rijtje...

2, 8, 24, 64, 160, 384, 896, 2048, 4608, 10240, 22528, 49152, 106496, 229376, 491520, ...

## zaterdag 11 februari 2017

### Rijtje enen

Every string of 1's:

1
11
111
1111
11111

… is a palindromic triangular number in base nine.

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## vrijdag 10 februari 2017

### Bach en nummer 14

The cantata he composed especially for this service comprised two parts, which were performed before and after the sermon. The two parts are divided in turn into 14 sections – the Bach number. If you number all the letters of the alphabet from 1 to 26 and then add up the values of the b, a, c and h, you get 14. Bach often used this number as a sort of signature.
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