|
%I #9 Dec 18 2021 14:53:33
%S 2,3,2,5,4,3,7,6,5,4,11,10,9,8,7,13,12,11,10,9,8,17,16,15,14,13,12,11,
%T 19,18,17,16,15,14,13,12,23,22,21,20,19,18,17,16,15,29,28,27,26,25,24,
%U 23,22,21,20,31,30,29,28,27,26,25,24,23,22,21,37,36,35,34,33,32,31,30,29,28,27,26
%N Write 1st prime and decrement 0 times, then write 2nd prime and decrement once, write 3rd prime and decrement twice, write 4th prime and decrement 3 times, etc ...
%D J.-P. Delahaye, Des suites fractales d’entiers, Pour la Science, No. 531 January 2022. Sequence b) p. 82.
%e As a triangle, this begins:
%e [2]
%e [3, 2]
%e [5, 4, 3]
%e [7, 6, 5, 4]
%e [11, 10, 9, 8, 7]
%e [13, 12, 11, 10, 9, 8]
%e [17, 16, 15, 14, 13, 12, 11]
%e [19, 18, 17, 16, 15, 14, 13, 12]
%e [23, 22, 21, 20, 19, 18, 17, 16, 15]
%e ...
%p a:=[];
%p for n from 1 to 16 do
%p t1:=[seq(ithprime(n)-i,i=0..n-1)];
%p lprint(t1);
%p a:=[op(a),op(t1)];
%p od:
%p a; # _N. J. A. Sloane_, Dec 18 2021
%o (Python)
%o from sympy import prime
%o from itertools import count, islice
%o def agen():
%o for i in count(1):
%o pi = prime(i)
%o yield from range(pi, pi-i, -1)
%o print(list(islice(agen(), 69))) # _Michael S. Branicky_, Dec 18 2021
%Y Cf. A000040.
%K nonn,tabf
%O 1,1
%A _Michel Marcus_, Dec 18 2021
|
