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A250478 Number of times prime(n) occurs as the least prime factor among numbers 1 .. prime(n)^4: a(n) = A078898(A030514(n)). 5
8, 14, 42, 92, 305, 455, 944, 1238, 2085, 3995, 4710, 7757, 10273, 11558, 14742, 20701, 28019, 30444, 39680, 46534, 49856, 62350, 71394, 86977, 111352, 124421, 130649, 145076, 151939, 167759, 236113, 257098, 291830, 302611, 370060, 382610, 427214, 475078 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Jon E. Schoenfield, Table of n, a(n) for n = 1..100

FORMULA

a(n) = A078898(A030514(n)).

a(1) = 1, a(n) = sum_{d | A002110(n-1)} moebius(d) * floor(prime(n)^3 / d). [Follows when A030514, prime(n)^4 is substituted to the similar formula given for A078898. Here A002110(n) gives the product of the first n primes. Because the latter is always squarefree, one could use here also Liouville's lambda (A008836) instead of Moebius mu (A008683).]

PROG

(PARI)

allocatemem(234567890);

A002110(n) = prod(i=1, n, prime(i));

A250478(n) = { my(p3); p3 = (prime(n)^3); sumdiv(A002110(n-1), d, (moebius(d)*(p3\d))); };

for(n=1, 23, print1(A250478(n), ", "));

(Scheme) (define (A250478 n) (A078898 (A030514 n)))

CROSSREFS

Column 8 of A249822.

Cf. also A250474 (column 4), A250477 (column 6).

Cf. A002110, A030514, A030078, A078898.

Sequence in context: A257709 A121866 A301961 * A059676 A242198 A111050

Adjacent sequences:  A250475 A250476 A250477 * A250479 A250480 A250481

KEYWORD

nonn

AUTHOR

Antti Karttunen, Dec 14 2014

EXTENSIONS

More terms from Jon E. Schoenfield, Dec 14 2014

STATUS

approved

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Last modified February 27 13:18 EST 2020. Contains 332306 sequences. (Running on oeis4.)