A357670 Sliding numbers which are products of three distinct primes.

70, 110, 290, 1001, 1010, 1258, 3157, 3445, 5002, 6266, 6410, 50002, 1958245, 2000005, 9766649, 9775865, 20000005, 48830173, 200000005, 488283298, 2000000005, 2441410346, 6103679465, 10000000001, 12207039442, 30517905805, 50000000002, 61035172634, 152588545985, 200000000005, 305175814018

Offset

1,1

Comments

A squarefree subsequence of numbers of the form p + q where 1/p + 1/q = (p + q)/10^k for some k >= 1.

Links

Table of n, a(n) for n=1..31.

Example

70 = 2*5*7 (70 = 20 + 50 and 1/20 + 1/50 = 0.070).
1001 = 7*11*13 (1001 = 1 + 1000 and 1/1 + 1/1000 = 1.001).
9766649 = 29*61*5521 (9766649 = 1024 + 9765625 and 1/1024 + 1/9765625 = 0.0009766649).
200000005 = 5*53*754717 (200000005 = 5 + 200000000 and 1/5 + 1/200000000 = 0.200000005).

Crossrefs

Intersection of A103182 and A007304.

Sequence in context: A044002 A117350 A004239 * A185817 A260573 A224672

Adjacent sequences: A357667 A357668 A357669 * A357671 A357672 A357673

Keyword

nonn,base

Author

Massimo Kofler, Oct 08 2022

Extensions

More terms from Hugo Pfoertner, Oct 08 2022

Status

approved