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 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. 2
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 OFFSET 1 COMMENTS Characteristic function for the range of A037019. LINKS Antti Karttunen, Table of n, a(n) for n = 1..107520 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]

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Last modified October 21 03:24 EDT 2019. Contains 328291 sequences. (Running on oeis4.)