OFFSET
1,1
COMMENTS
For each term p=a(n), the corresponding greater member is q=A072743(n).
LINKS
Michel Marcus, Table of n, a(n) for n = 1..8217
EXAMPLE
n p = a(n) q = A072743(n) (p+q)/2
-- -------- -------------- ---------
1 3 5 4 = 2^2
2 5 11 8 = 2^3
3 13 19 16 = 2^4
4 17 47 32 = 2^5
5 23 41 32 = 2^5
6 61 67 64 = 2^6
7 83 173 128 = 2^7
8 89 167 128 = 2^7
9 107 149 128 = 2^7
10 139 373 256 = 2^8
As an irregular triangle, sequence begins:
[3], (k=2)
[5], (k=3)
[13], (k=4)
[17, 23], (k=5)
[61], (k=6)
[83, 89, 107], (k=7)
[139, 163, 181, 199, 229, 241], (k=8)
...
PROG
(PARI) listk(k) = {my(list = List()); forprime(p=2^(k-1)+1, 2^k, my(q=2^(k+1)-p); if ((q>p) && isprime(q), listput(list, p)); ); Vec(list); }
upto(k) = {my(list = List()); for (i=1, k, my(klist = listk(i)); if (#klist, for (j=1, #klist, listput(list, klist[j]))); ); Vec(list); }
upto(11) \\ Michel Marcus, Jan 22 2022
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Reinhard Zumkeller, Jul 08 2002
EXTENSIONS
Name corrected by Jon E. Schoenfield, Jun 27 2021
More terms from Michel Marcus, Jan 22 2022
STATUS
approved