A101896 Primes obtained if 2^j for some suitable j is written backward.

2, 61, 23, 821, 4201, 270131, 61277761, 274359834731, 23888027348153, 86936981079782063, 4243031147170261950811, 272838646828154727511151, 821882010875193363312928672952261, 274562423560500997742392394025368175422471, 4266472836315949449695828501889595072967427241

Offset

1,1

Comments

The relevant exponents are collected in A057708.

a(23), reverse(2^3489), has 1023 decimal digits. - Michael De Vlieger, Dec 03 2015

Links

Michael De Vlieger, Table of n, a(n) for n = 1..22

Formula

a(n) = reverse(2^A057708(n)).

Example

Reverse 128, obtain 821, a prime.

Mathematica

Select[FromDigits@ Reverse@ IntegerDigits[2^#] & /@ Range@ 3200, PrimeQ] (* Michael De Vlieger, Dec 03 2015 *)

Prog

(GAP) a:=Filtered(List(List([1..300], j->Reversed(ListOfDigits(2^j))), k->Sum([1..Size(k)], i->k[i]*10^(Size(k)-i))), IsPrime);; Print(a); # Muniru A Asiru, Dec 25 2018

Crossrefs

Cf. A057708.

Sequence in context: A121493 A078491 A182856 * A130411 A262079 A364659

Adjacent sequences: A101893 A101894 A101895 * A101897 A101898 A101899

Keyword

base,nonn

Author

Labos Elemer, Jan 28 2005

Status

approved