This site is supported by donations to The OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A140755 Square array read by rows: T(n,k) = 41*n^2 + k^2 + n*k, with 20 columns. 4
 43, 47, 53, 61, 71, 83, 97, 113, 131, 151, 173, 197, 223, 251, 281, 313, 347, 383, 421, 461, 167, 172, 179, 188, 199, 212, 227, 244, 263, 284, 307, 332, 359, 388, 419, 452, 487, 524, 563, 604, 373, 379, 387, 397, 409, 423, 439 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The original definition of this sequence was obscure: "A prime array is embedded in a binary quadratic equation that is a transform of x^2 -x + 41". LINKS FORMULA 41b^2 + ab + a^2, a = column 1:20, b = row 1:8, factor the row number b starting at b = 2 and remove all prime factors in b (on row 2 just 2's) from all terms on the row. Repeat the process for all rows. The numbers that remain at the end of the process in the 20*8 array will all be prime EXAMPLE a = 16, b = 2, S(16,2) = 452, 452/2 = 226, 226/2 = 113 (a prime} a = 6, b = 3, S(6,3) = 423, 423/3 = 141, 141/3 = 47 (a prime} a = 6, b = 6, S(6,6) = 1548, 1548/2 = 774, 774/2 = 387, 387/3 = 129, 129/3 = 43 (a prime} CROSSREFS Cf. A140754, A140340 (very similar arrays). Sequence in context: A095503 A095495 A095487 * A095479 A156783 A273595 Adjacent sequences:  A140752 A140753 A140754 * A140756 A140757 A140758 KEYWORD nonn,tabf AUTHOR Aldrich Stevens (aldrichstevens(AT)msn.com), May 27 2008 EXTENSIONS Partially edited with better definition by Omar E. Pol, Jan 11 2009 More terms from Omar E. Pol, Jan 11 2009 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 November 19 11:46 EST 2019. Contains 329319 sequences. (Running on oeis4.)