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

1,1

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

Links

Table of n, a(n) for n=1..83.

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

Example

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

Prog

(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

Crossrefs

Cf. A001358, A228355.

Sequence in context: A141569 A200621 A210665 * A200107 A198733 A010478

Adjacent sequences: A228583 A228584 A228585 * A228587 A228588 A228589

Keyword

nonn,base,easy,cons

Author

Jonathan Vos Post, Aug 26 2013

Status

approved