A323509 a(n) = 1 if n = 2^e1 * 3^e2 * ... * prime(k)^e_k, with k = A061395(n) = A001221(n) and e1 >= e2 >= ... >= e_k, with each e1 .. e_k one less than a prime, otherwise a(n) = 0.

1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1

Comments

Characteristic function for the range of A037019.

Links

Antti Karttunen, Table of n, a(n) for n = 1..107520

Index entries for characteristic functions

Formula

a(A037019(n)) = 1.

a(n) <= A322585(n).

Prog

(PARI) A323509(n) = { my(f = factor(n)); for(i=1, #f~, if((primepi(f[i, 1])!=i)||!isprime(1+f[i, 2])||((i>1)&&(f[i-1, 2]<f[i, 2])), return(0))); (1); };

Crossrefs

Cf. A037019, A322585.

Cf. also A323510.

Sequence in context: A185175 A322586 A147612 * A197183 A357382 A295405

Adjacent sequences: A323506 A323507 A323508 * A323510 A323511 A323512

Keyword

nonn

Author

Antti Karttunen, Jan 18 2019

Status

approved