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 A284318 Triangle read by rows in which row n lists divisors d of n such that n divides d^n. 3
 1, 2, 3, 2, 4, 5, 6, 7, 2, 4, 8, 3, 9, 10, 11, 6, 12, 13, 14, 15, 2, 4, 8, 16, 17, 6, 18, 19, 10, 20, 21, 22, 23, 6, 12, 24, 5, 25, 26, 3, 9, 27, 14, 28, 29, 30, 31, 2, 4, 8, 16, 32, 33, 34, 35, 6, 12, 18, 36, 37, 38, 39, 10, 20, 40, 41, 42, 43, 22, 44, 15, 45, 46, 47, 6, 12, 24, 48, 7, 49, 10, 50 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Row n lists divisors of n that are divisible by A007947(n). - Robert Israel, Apr 27 2017 LINKS Robert Israel, Table of n, a(n) for n = 1..10002  (rows 1 to 5250, flattened) FORMULA T(n,k) = A007947(n) * A027750(A003557(n), k). - Robert Israel, Apr 27 2017 EXAMPLE Triangle begins:     1;     2;     3;     2, 4;     5;     6;     7;     2, 4, 8;     3, 9;     10;     11;     6, 12;     13;     14;     15;     2, 4, 8, 16. MAPLE f:= proc(n) local r;     r:= convert(numtheory:-factorset(n), `*`);     op(sort(convert(map(`*`, numtheory:-divisors(n/r), r), list))) end proc: map(f, [\$1..100]); # Robert Israel, Apr 27 2017 MATHEMATICA Flatten[Table[Select[Range[n], Divisible[n, #] && Divisible[#^n, n] &], {n, 50}]] (* Indranil Ghosh, Mar 25 2017 *) PROG (MAGMA) [[u: u in [1..n] | Denominator(n/u) eq 1 and Denominator(u^n/n) eq 1]: n in [1..50]]; (PARI) for(n=1, 50, for(i=1, n, if(n%i==0 & (i^n)%n==0, print1(i, ", "); ); ); print(); ); \\ Indranil Ghosh, Mar 25 2017 (Python) for n in xrange(1, 51): ....print [i for i in xrange(1, n + 1) if n%i==0 and (i**n)%n==0] # Indranil Ghosh, Mar 25 2017 CROSSREFS Cf. A000961 (1 together with k such that k divides p^k for some prime divisor p of k), A005361 (row length), A007774 (m such that m divides s^m for some semiprime divisor s of m), A007947 (smallest u such that u^n|n and n|u, or divisor k such that A000005(k) = 2^A001221(n)), A057723 (row sums), A066503 (difference between largest x and smallest y such that x^n|n, n|x, y^n|n and n|y). Cf. A003557, A027750. Sequence in context: A227842 A304731 A304728 * A322791 A304745 A176789 Adjacent sequences:  A284315 A284316 A284317 * A284319 A284320 A284321 KEYWORD nonn,tabf AUTHOR Juri-Stepan Gerasimov, Mar 25 2017 STATUS approved

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Last modified September 22 16:41 EDT 2019. Contains 327311 sequences. (Running on oeis4.)