The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A274048 a(n) = A116640(A018900(n)). 0
 19, 23, 29, 31, 37, 49, 47, 53, 65, 89, 79, 85, 97, 121, 169, 143, 149, 161, 185, 233, 329, 271, 277, 289, 313, 361, 457, 649, 527, 533, 545, 569, 617, 713, 905, 1289, 1039, 1045, 1057, 1081, 1129, 1225, 1417, 1801 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A subset of A116640 containing all terms A116640(m) such that m has binary weight of 2. This sequence is related to the Collatz and Terras trajectories; specifically those trajectories that include three odd numbers besides 1. LINKS FORMULA a(n) = 2^(Row(n)+1) + 3*(3+2^Col(n)) where Row(n) = A002024(n) = the row position of n when the sequence is viewed as a regular triangle; and Col(n) = A002260(n) = the column position of n when the sequence is viewed as a regular triangle. EXAMPLE The first three terms of A018900 are 3,5,6. Taking these terms from A116640 gives 19,23,29, which are the first three terms of this sequence. The sequence is generated from the regular triangle 1; 1,2; 1,2,3; etc., so the first three terms are 2^(1+1) + 3*(3+2^1) = 19; 2^(2+1) + 3*(3+2^1) = 23; 2^(2+1) + 3*(3+2^2)= 29. CROSSREFS Cf. A116640, A116623. Sequence in context: A166061 A224534 A073319 * A334093 A120640 A309360 Adjacent sequences:  A274045 A274046 A274047 * A274049 A274050 A274051 KEYWORD nonn,easy,tabl AUTHOR Joe Slater, Jun 07 2016 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 January 25 05:31 EST 2021. Contains 340416 sequences. (Running on oeis4.)