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A025471
Position of 5^n among the powers of primes (A000961).
0
1, 5, 15, 43, 137, 483, 1881, 7772, 33292, 146014, 650688, 2935909, 13377899, 61448617, 284148766, 1321470026, 6175996065, 28988110806, 136575209239, 645621236243, 3061130340023, 14552991533455, 69354804657255, 331251331834172, 1585299655420744, 7600886382041555, 36504944105963117
OFFSET
0,2
FORMULA
a(n) = A065515(5^n). - Michel Marcus, Mar 24 2013
PROG
(PARI) a(n) = n=5^n; 1+sum(k=1, logint(n, 2), primepi(sqrtnint(n, k))); \\ Daniel Suteu, Dec 15 2019
CROSSREFS
Cf. A000351 (powers of 5), A000961, A065515.
Sequence in context: A032193 A178965 A005665 * A064453 A059251 A295179
KEYWORD
nonn
EXTENSIONS
a(13)-a(20) from Robert G. Wilson v, Dec 13 2019
a(21)-a(26) from Daniel Suteu, Dec 15 2019
STATUS
approved