The OEIS is supported by the many generous donors to the OEIS Foundation.

 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 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A067528 Numbers n such that n - 4^k is a prime or 1 for all k > 0 and n > 4^k. 5
 5, 6, 7, 9, 11, 15, 17, 21, 23, 27, 33, 35, 45, 47, 57, 63, 75, 77, 83, 87, 105, 117, 143, 153, 167, 195, 215, 227, 243, 245, 255, 287, 297, 413, 437, 447, 483, 495, 507, 525, 573, 635, 657, 677, 755, 825, 1113, 1133, 1295, 1487, 1515, 1547, 1617, 1623, 2015 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Is the sequence finite? The last term appears to be 5833497. - T. D. Noe, Nov 23 2004 A less strict version of A039669, n - 2^k is prime for 0 < k < log_2 k. If a number is in that sequence, then obviously it is also in this sequence. As of this writing, 105 is believed to be the last term of that sequence. - Alonso del Arte, May 24 2017 LINKS T. D. Noe, Table of n, a(n) for n=1..102 (no others < 2*10^9) EXAMPLE 167 is a term as 167 - 4 = 163, 167 - 16 = 151, 167 - 64 = 103 are primes. MAPLE filter:= proc(n) local k, t; for k from 1 do if 4^k >= n-1 then return true elif not isprime(n-4^k) then return false fi od end proc: select(filter, [\$5..3000]); # Robert Israel, May 24 2017 MATHEMATICA A067528 = {}; Do[k = 1; While[p = n - 4^k; p > 0 && (p == 1 || PrimeQ[p]), k++]; If[p <= 0, AppendTo[A067528, n]], {n, 5, 10^7}]; A067528 (* T. D. Noe *) CROSSREFS Cf. A067526. Sequence in context: A355239 A030388 A031059 * A287087 A180939 A229231 Adjacent sequences: A067525 A067526 A067527 * A067529 A067530 A067531 KEYWORD nonn AUTHOR Amarnath Murthy, Feb 17 2002 EXTENSIONS More terms from Sascha Kurz, Mar 19 2002 STATUS approved

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

Last modified December 9 17:09 EST 2023. Contains 367693 sequences. (Running on oeis4.)