login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A254248 Number of terms in A006285 (de Polignac numbers) less than 10^n. 5
0, 1, 1, 18, 262, 3393, 39541, 421863, 4457974, 46853770, 482301801, 4931928485 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

a(n) < 10^n*exp(-(n*log(10))^c) for some c.

LINKS

Table of n, a(n) for n=0..11.

Carlos Rivera, Puzzle 219. Polignac numbers, The Prime Puzzles and Problems Connection.

MATHEMATICA

dePolignacQ[n_] := OddQ[n] && Module[{m = 2}, While[n > m + 1 && ! PrimeQ[n - m], m *= 2]; n <= m + 1]; seq[max_] := Module[{p = 10, c = 1, s = {0}}, Do[If[dePolignacQ[k], c++]; If[k == p, p *= 10; AppendTo[s, c]], {k, 5, 10^max}]; s]; seq[6] (* Amiram Eldar, Feb 04 2021 *)

CROSSREFS

Cf. A006285, A255816, A255971, A256164, A256238.

Sequence in context: A255381 A078205 A316698 * A080583 A273589 A076693

Adjacent sequences:  A254245 A254246 A254247 * A254249 A254250 A254251

KEYWORD

nonn,more

AUTHOR

Arkadiusz Wesolowski, Mar 16 2015

EXTENSIONS

a(9) from Arkadiusz Wesolowski, Feb 09 2016

a(10)-a(11) from Amiram Eldar, Feb 04 2021

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 30 20:17 EST 2021. Contains 349425 sequences. (Running on oeis4.)