A280895 For any n>=0, least prime k = p^d-2*n, where p is a prime and d is its number of digits.

2, 3, 3, 163, 113, 1030291, 109, 107, 2571337, 103, 101, 2248069, 97, 263, 1442869, 139, 89, 1225009, 2685583, 83, 2571313, 79, 317, 2571307, 73, 71, 1224991, 67, 113, 3307891, 61, 59, 104633567005988371387, 103, 53, 1224973, 97, 47, 1224967, 43, 41, 1030219, 37

Offset

0,1

Links

Paolo P. Lava, Table of n, a(n) for n = 0..1000

Example

a(5) = 1030291 because 1030291 is the least prime such that 101^3 - 2*5 = 1030301 - 10 = 1030291.

Maple

P:=proc(q) local a, b, k, n; for n from 0 to q do for k from 1 to q do a:=ithprime(k);
b:=a^(ilog10(a)+1)-2*n; if isprime(b) then lprint(n, b); break; fi; od; od; end: P(1000);

Crossrefs

Cf. A055642, A280427

Sequence in context: A214219 A365223 A323340 * A088266 A116889 A347716

Adjacent sequences: A280892 A280893 A280894 * A280896 A280897 A280898

Keyword

nonn,base

Author

Paolo P. Lava, Jan 10 2017

Status

approved