[seqfan] OEIS advanced searches with wildcards.

[Antti Karttunen]

Cheers,

here are two nice search-tips for advanced searches. To search for
"sigma-like" sequences (defined here ad hoc as sequences with a(1) =
1, and a(p) = 1+p for all primes), just enter 1,3,4,_,6,_,8, _, _,
_,12, _,14, _, _, _,18, _, 20, _, _, _, 24
to the search-field, like this:

https://oeis.org/search?q=1%2C3%2C4%2C_%2C6%2C_%2C8%2C+_%2C+_%2C+_%2C12%2C+_%2C14%2C+_%2C+_%2C+_%2C18%2C+_%2C+20%2C+_%2C+_%2C+_%2C+24&sort=&language=&go=Search

Similarly, to search for "phi-like" sequences (defined here just as
sequences with a(1) = 1, and a(p) = p-1 for all primes), just enter

1,1,2,_,4,_,6, _, _, _,10, _,12, _, _, _,16, _, 18, _, _, _, 22, _, _,
_, _, _, 28, _, 30 keyword:mult

to search-field (but with keyword:mult added for the better
signal/noise ratio), like this:

https://oeis.org/search?q=1%2C1%2C2%2C_%2C4%2C_%2C6%2C+_%2C+_%2C+_%2C10%2C+_%2C12%2C+_%2C+_%2C+_%2C16%2C+_%2C+18%2C+_%2C+_%2C+_%2C+22%2C+_%2C+_%2C+_%2C+_%2C+_%2C+28%2C+_%2C+30+keyword%3Amult&sort=&language=&go=Search

Now, a funny quirk: Why in the results of the first search all the
first 23 terms appear in bold, while in the second search only the
non-wildcard matches (i.e., at 1 and prime-positions up to p=31) do?
(Hmm, apparently it's the effect of that additional keyword:mult among
the search-terms. There must be some logic in that... But never mind,
the results are nice in any case!)

And here for finding the sequences that have a(p) = 1, at least for
the initial eleven primes 2 .. 31, among many other seqs also:
_,1,1,_,1,_,1, _, _, _,1, _,1, _, _, _,1, _, 1, _, _, _, 1, _, _, _,
_, _, 1, _, 1

https://oeis.org/search?q=_%2C1%2C1%2C_%2C1%2C_%2C1%2C+_%2C+_%2C+_%2C1%2C+_%2C1%2C+_%2C+_%2C+_%2C1%2C+_%2C+1%2C+_%2C+_%2C+_%2C+1%2C+_%2C+_%2C+_%2C+_%2C+_%2C+1%2C+_%2C+1&sort=&language=&go=Search


Have fun!

Best regards,

Antti