

A072037


Palindromic powers (with positive exponents) of a prime but not a prime (A025475).


3



4, 8, 9, 121, 343, 1331, 10201, 14641, 94249, 1030301, 104060401, 900075181570009, 10022212521222001, 12124434743442121, 12323244744232321, 12341234943214321, 1022321210249420121232201, 1210024420147410244200121, 1210222232227222322220121
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..19.


EXAMPLE

E.g. 94249=307*307


MATHEMATICA

a = {}; Do[pp = Prime[n]^i; d = IntegerDigits[pp]; If[d == Reverse[d], a = Append[a, pp]], {n, 1, PrimePi[ Sqrt[10^21]]}, {i, 2, Floor[ Log[ Prime[n], 10^21]]}]; Sort[a] (Robert G. Wilson v)


PROG

(PARI) {a=10^15; v=[]; m=sqrt(a); forprime(p=2, m, q=p; while((q=q*p)<a, n=q; rev=0; while(n>0, d=divrem(n, 10); n=d[1]; rev=10*rev+d[2]); if(q==rev, v=concat(v, q)))); v=vecsort(v); for(j=1, matsize(v)[2], print1(v[j], ", "))}


CROSSREFS

Cf. A025475, A002385.
Sequence in context: A046450 A077271 A084093 * A076703 A305372 A261602
Adjacent sequences: A072034 A072035 A072036 * A072038 A072039 A072040


KEYWORD

base,easy,nonn


AUTHOR

Labos Elemer, Jun 07 2002


EXTENSIONS

Two more term from Klaus Brockhaus, Jun 07 2002
Four more terms from Robert G. Wilson v, Oct 31 2002
Added a(17)a(19), clarified definition, Donovan Johnson, Sep 01 2012


STATUS

approved



