A228586 Write the semiprimes backwards in base 10 and juxtapose (concatenate) their digits.

4, 6, 9, 0, 1, 4, 1, 5, 1, 1, 2, 2, 2, 5, 2, 6, 2, 3, 3, 4, 3, 5, 3, 8, 3, 9, 3, 6, 4, 9, 4, 1, 5, 5, 5, 7, 5, 8, 5, 2, 6, 5, 6, 9, 6, 4, 7, 7, 7, 2, 8, 5, 8, 6, 8, 7, 8, 1, 9, 3, 9, 4, 9, 5, 9, 6, 0, 1, 1, 1, 1, 5, 1, 1, 8, 1, 1, 9, 1, 1, 1, 2, 1

Offset: 1

Author

Jonathan Vos Post, Aug 26 2013

Keywords

• nonn
• base
• easy
• cons

Comments

Also, decimal expansion of the constant 0.46901415112225262... This is to A228355 as semiprimes A001358 are to prime A000040.

A theorem of Copeland & Erdős proves that this constant is 10-normal. - Charles R Greathouse IV, Feb 06 2015

Examples

			4, 6, 9, 01, 41, 51, 12, 22, 52, 62, 33, 43, 53, 83, 93, 64, 94, 15, 55,...
		

Links

• A. H. Copeland and P. Erdős, Note on normal numbers, Bull. Amer. Math. Soc. 52 (1946), pp. 857-860.

Crossrefs

Cf. A001358, A228355.

Programs

PARI

print1(4); for(n=6, 121, if(bigomega(n)==2, d=Vecrev(digits(n)); for(i=1, #d, print1(", "d[i])))) \\ Charles R Greathouse IV, Feb 06 2015