A273007 a(n) is the smallest exponent > 1 such that p^a(n) ends with p, where p is the n-th prime.

5, 5, 2, 5, 11, 21, 21, 11, 21, 11, 11, 21, 6, 5, 21, 21, 11, 6, 21, 11, 21, 11, 21, 11, 21, 11, 101, 21, 51, 101, 101, 51, 101, 51, 11, 11, 21, 101, 101, 101, 51, 51, 51, 5, 101, 11, 51, 101, 101, 51, 101, 51, 26, 3, 21, 101, 51, 51, 101, 26, 101, 21, 5, 51

Offset

1,1

Links

Paolo P. Lava, Table of n, a(n) for n = 1..1000

Example

2^2 = 4, 2^3 = 8, 2^4 = 16, 2^5 = 32;
3^2 = 9, 3^3 = 27, 3^4 = 81, 3^5 = 243.

Maple

P:=proc(q) local d, k, n; for n from 1 to q do if isprime(n) then d:=ilog10(n)+1;
for k from 2 to q do if n=(n^k mod 10^d) then print(k); break; fi; od; fi; od; end: P(10^3);

Mathematica

Table[Length[NestWhileList[p #&, p^2, Mod[#, 10^IntegerLength[p]]!=p&]]+1, {p, Prime[ Range[65]]}] (* Harvey P. Dale, Jul 25 2019 *)

Crossrefs

Cf. A051248, A115739, A273527.

Sequence in context: A011335 A021185 A132376 * A316168 A019602 A153839

Adjacent sequences: A273004 A273005 A273006 * A273008 A273009 A273010

Keyword

nonn,easy,base

Author

Paolo P. Lava, May 24 2016

Status

approved