[seqfan] Rif: Re: Rif: Re: Insert "+" and always get a prime

[john.mason at lispa.it]

I hope I'm not exagerating, but

1. some numbers satisfy both the + and - conditions:
14, 16, 20, 25, 29, 30, 38, 41, 47, 49, 50, 52, 58, 61, 70, 74,
83, 85, 92, 94, 118, 130, 245, 310, 334, 356, 370, 376, 518, 536,
665, 667, 710, 730, 736, 754, 790, 845, 970, 992, 2465, 3310, 3370,
3730, 7390, 66667, 339370

2. some numbers satisfying the + condition are prime themselves
11, 23, 29, 41, 43, 47, 61, 67, 83, 89, 227, 229, 281, 443,
449, 467, 647, 661, 683, 821, 863, 881, 2221, 2267, 2281, 2447,
4229, 4463, 4643, 8221, 8821, 26881, 28429, 68683, 282881, 282889,
464447, 626261, 864883, 6462667, 6866683

3. some numbers satisfying the - condition are prime themselves
13, 29, 31, 41, 47, 53, 61, 79, 83, 97, 263, 269, 421, 463,
487, 643, 2663, 2729, 4663, 6163, 6269, 6563, 6689, 6863, 8669,
24623, 46867, 68669, 426421, 664669

I don't think there are many more ...

john

__________________________________



Da:     Hans Havermann <gladhobo at teksavvy.com>
Per:    Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
Data:   23/12/2014 11:34
Oggetto:        [seqfan] Re: Rif:  Re: Insert "+" and always get a prime
Inviato da:     "SeqFan" <seqfan-bounces at list.seqfan.eu>



John Mason:

> Continuing Lars's calculations for the "plus" variety:
> 15177112, ... 117711170

That takes us to #424. There can't be many more. ;)

425 222866845
426 331111958
427 511151552
428 593559374
429 622888465
430 773719910
431 882428665
432 995955112
433 1777137770
434 5753779594
435 6464886245
436 9151995592
437 22226226625
438 31993717930
439 39393115598
440 46884486265

I've got nothing else to 10^12 but I'll go to 10^13 just in case.


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