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A355925 Square array A(n, k) = A009194(A246278(n, k)), read by falling antidiagonals.

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%I A355925 #14 Jul 24 2022 10:45:29
%S A355925 1,1,1,6,1,1,1,3,1,1,2,1,1,1,1,4,1,1,1,1,1,2,3,1,1,1,1,1,1,3,1,7,1,1,
%T A355925 1,1,3,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,12,1,
%U A355925 1,7,1,1,1,1,1,1,1,1,2,15,1,7,1,1,1,1,1,1,1,1,1,28,3,1,1,1,1,1,1,1,1,1,1,1,1
%N A355925 Square array A(n, k) = A009194(A246278(n, k)), read by falling antidiagonals.
%H A355925 Antti Karttunen, <a href="/A355925/b355925.txt">Table of n, a(n) for n = 1..22155; the first 210 antidiagonals</a>
%H A355925 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H A355925 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A355925 A(n, k) = A009194(A246278(n, k)).
%F A355925 A(n, k) = gcd(A246278(n,k), A355927(n, k)).
%F A355925 A(n, k) = A355927(n, k) / A341605(n, k).
%F A355925 A(n, k) = A246278(n, k) / A341606(n, k).
%e A355925 The top left corner of the array:
%e A355925    k=  1  2  3  4  5  6  7  8  9 10  11  12 13  14 15 16 17 18  19  20 21
%e A355925   2k=  2  4  6  8 10 12 14 16 18 20  22  24 26  28 30 32 34 36  38  40 42
%e A355925 -----+-----------------------------------------------------------------------
%e A355925    1 | 1, 1, 6, 1, 2, 4, 2, 1, 3, 2,  2, 12, 2, 28, 6, 1, 2, 1,  2, 10, 6,
%e A355925    2 | 1, 1, 3, 1, 1, 3, 3, 1, 1, 1,  1, 15, 3,  3, 3, 1, 1, 1,  3,  1, 3,
%e A355925    3 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 5,  1, 1, 1, 1, 1,  5,  1, 7,
%e A355925    4 | 1, 1, 1, 1, 7, 1, 1, 1, 7, 7,  1,  1, 1,  1, 7, 1, 1, 7,  1,  7, 1,
%e A355925    5 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1, 19, 1, 1, 1, 1,  1,  1, 1,
%e A355925    6 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1, 17, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925    7 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925    8 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 19,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925    9 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   10 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   11 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1, 37, 1,  1, 1, 1, 1, 1, 31,  1, 1,
%e A355925   12 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   13 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   14 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   15 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1, 61, 1, 1, 1, 1,  1,  1, 1,
%e A355925   16 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   17 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   18 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   19 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   20 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%e A355925   21 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1, 1,  1, 1, 1, 1, 1,  1,  1, 1,
%o A355925 (PARI)
%o A355925 up_to = 105;
%o A355925 A009194(n) = gcd(n, sigma(n));
%o A355925 A246278sq(row,col) = if(1==row,2*col, my(f = factor(2*col)); for(i=1, #f~, f[i,1] = prime(primepi(f[i,1])+(row-1))); factorback(f));
%o A355925 A355925sq(row,col) = A009194(A246278sq(row,col));
%o A355925 A355925list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A355925sq(col,(a-(col-1))))); (v); };
%o A355925 v355925 = A355925list(up_to);
%o A355925 A355925(n) = v355925[n];
%Y A355925 Cf. A000203, A009194, A246278.
%Y A355925 Cf. also A341605, A341606, A341607, A341608, A341626, A341627, A355924, A355927 for related arrays of similar construction.
%K A355925 nonn,tabl
%O A355925 1,4
%A A355925 _Antti Karttunen_, Jul 22 2022