This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A228813 Triangle read by rows T(n,k) in which column k lists 1's interleaved with A004526(k-1) zeros starting from the row A002620(k+1), with n>=1, k>=1. 13
 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1 COMMENTS The sum of row n equals the number of divisors of n. The number of zeros in row n equals A078152(n). It appears that there are only eight rows that do not contain zeros. The indices of these rows are 1, 2, 3, 4, 6, 8, 12, 24, the divisors of 24, see A018253. It appears that A066522 gives the indices of the rows in which the elements are in nonincreasing order. LINKS EXAMPLE For n = 10, row 10 is [1, 1, 1, 1, 0], and the sum of row 10 is 1+1+1+1+0 = 4. On the other hand, 10 has four divisors: 1, 2, 5, and 10. Note that the sum of row 10 is also A000005(10) = 4, the number of divisors of 10. Triangle begins: 1; 1, 1; 1, 1; 1, 1, 1; 1, 1, 0; 1, 1, 1, 1; 1, 1, 0, 0; 1, 1, 1, 1; 1, 1, 0, 0, 1; 1, 1, 1, 1, 0; 1, 1, 0, 0, 0; 1, 1, 1, 1, 1, 1; 1, 1, 0, 0, 0, 0; 1, 1, 1, 1, 0, 0; 1, 1, 0, 0, 1, 1; 1, 1, 1, 1, 0, 0, 1; 1, 1, 0, 0, 0, 0, 0; 1, 1, 1, 1, 1, 1, 0; 1, 1, 0, 0, 0, 0, 0; 1, 1, 1, 1, 0, 0, 1, 1; 1, 1, 0, 0, 1, 1, 0, 0; 1, 1, 1, 1, 0, 0, 0, 0; 1, 1, 0, 0, 0, 0, 0, 0; 1, 1, 1, 1, 1, 1, 1, 1; ... CROSSREFS Row sums give A000005. Row n has length A055086(n). Columns 1 and 2: A000012. Columns 3 and 4: A059841. Columns 5 and 6: A079978. Columns 7 and 8: A121262. Columns 9 and 10: A079998. Columns 11 and 12: A079979. Columns 13 and 14: A082784. Cf. A002620, A004526, A018253, A027750, A066522, A078152, A147861, A161904, A196020, A210959, A212119, A212120, A221645, A228812, A228814. Sequence in context: A131364 A152066 A225595 * A122255 A122261 A014922 Adjacent sequences:  A228810 A228811 A228812 * A228814 A228815 A228816 KEYWORD nonn,tabf AUTHOR Omar E. Pol, Sep 29 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 15 12:31 EDT 2019. Contains 328026 sequences. (Running on oeis4.)