cp's OEIS Frontend

A371102 Array A read by upward antidiagonals in which the entry A(n,k) in row n and column k is defined by A(1, k) = 4*k-1, and A(n+1, k) = A371094(A(n, k)), n,k >= 1.

%I A371102 #5 Apr 21 2024 14:29:09
%S A371102 3,21,7,5461,45,11,357913941,1109,69,15,1537228672809129301,873813,
%T A371102 3413,93,19,28356863910078205288614550619314017621,1466015503701,
%U A371102 22369621,2261,117,23,9649340769776349618630915417390658987772498722136713669954798667326094136661,25790417485112089060398421,6004799503160661,873813,11605,141,27
%N A371102 Array A read by upward antidiagonals in which the entry A(n,k) in row n and column k is defined by A(1, k) = 4*k-1, and A(n+1, k) = A371094(A(n, k)), n,k >= 1.
%e A371102 Array begins:
%e A371102 n\k|         1       2         3       4         5         6         7
%e A371102 ---+--------------------------------------------------------------------
%e A371102 1  |         3,      7,       11,     15,       19,       23,       27,
%e A371102 2  |        21,     45,       69,     93,      117,      141,      165,
%e A371102 3  |      5461,   1109,     3413,   2261,    11605,     3413,     8021,
%e A371102 4  | 357913941, 873813, 22369621, 873813, 72701269, 22369621, 12408149,
%o A371102 (PARI)
%o A371102 up_to = 105;
%o A371102 A371094(n) = { my(m=1+3*n, e=valuation(m,2)); ((m*(2^e)) + (((4^e)-1)/3)); };
%o A371102 A371102sq(n,k) = if(1==n,4*k-1,A371094(A371102sq(n-1,k)));
%o A371102 A371102list(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] = A371102sq((a-(col-1)),col))); (v); };
%o A371102 v371102 = A371102list(up_to);
%o A371102 A371102(n) = v371102[n];
%Y A371102 Cf. A004767 (row 1), A102603 (row 2), A371094.
%Y A371102 Cf. also arrays A257852, A371096, A371100, A371103.
%K A371102 nonn,tabl,easy
%O A371102 1,1
%A A371102 _Antti Karttunen_, Apr 21 2024