A135625 Product of n-th Mersenne prime and n-th Mersenne prime written backwards.

9, 49, 403, 91567, 15710338, 22299240301, 410215255975, 16028490260973271564, 3675428737957071376458418697257441432, 68870283995769119153444423083582483731047501259451576, 117132053040627211700855551462169332419627937481594387132326105147, 123777964225587033644972609912682600644825032245501533642224841942296666013617

Offset: 1

Author

Omar E. Pol, Feb 20 2008

Keywords

• base
• nonn

Examples

			a(3) = 403 because the 3rd Mersenne prime is 31 and 31*13 = 403.
		

Links

• Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos.

Crossrefs

Cf. A000668, A133019, A135623.

Programs

Maple

read transforms : A000043 := proc(n) op(n,[2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203, 2281, 3217, 4253, 4423, 9689, 9941, 11213, 19937]) ; end: A000668 := proc(n) 2^A000043(n)-1 ; end: A135623 := proc(n) digrev(A000668(n)) ; end: A135625 := proc(n) A000668(n)*A135623(n) ; end: for n from 1 to 13 do printf("%d, ",A135625 (n) ) ; od: # R. J. Mathar, Feb 28 2008

Mathematica

# FromDigits[Reverse[IntegerDigits[#]]]&/@Select[2^Prime[Range[100]]-1, PrimeQ] (* Harvey P. Dale, Mar 26 2012 *)

Formula

a(n) = A000668(n)*A135623(n).

Extensions

More terms from R. J. Mathar, Feb 28 2008