

A328770


Numbers in whose primorial base expansion any digit is at most half of the maximal allowed digit for that position.


6



0, 2, 6, 8, 12, 14, 30, 32, 36, 38, 42, 44, 60, 62, 66, 68, 72, 74, 90, 92, 96, 98, 102, 104, 210, 212, 216, 218, 222, 224, 240, 242, 246, 248, 252, 254, 270, 272, 276, 278, 282, 284, 300, 302, 306, 308, 312, 314, 420, 422, 426, 428, 432, 434, 450, 452, 456, 458, 462, 464, 480, 482, 486, 488, 492, 494, 510, 512, 516, 518, 522
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OFFSET

1,2


COMMENTS

Equally, numbers in whose primorial base expansion there are no digits more than ((prime(k)1)/2), where prime(k) is the modulus for the digit position k = 1 + maximal allowed digit for that position.
Differs from A276154, for example, this sequence does not contain term 120.


LINKS

Antti Karttunen, Table of n, a(n) for n = 1..9072
Index entries for sequences related to primorial base


FORMULA

a(n) = A328849(n)/2.
Because doubling these numbers in primorial base does not generate any carries, it follows that:
A276086(a(n)+a(n)) = A276086(a(n)) * A276086(a(n)) = A328834(n)^2.


EXAMPLE

2 is included, as in the primorial base (A049345) it is written as "10", thus 2 is included in the sequence as the maximal value that can occur in the second rightmost digit (in the primorial base representation) is 2 (as in "20" = 4 or "21" = 5 for example).


PROG

(PARI) isA328770(n) = { my(p=2); while(n, if((n%p)>((p1)/2), return(0)); n = n\p; p = nextprime(1+p)); (1); };


CROSSREFS

Subsequence of A276154 (because of Bertrand's postulate).
Cf. A002110, A049345, A276086, A328834, A328849.
Sequence in context: A153880 A120227 A276154 * A138626 A178406 A189515
Adjacent sequences: A328767 A328768 A328769 * A328771 A328772 A328773


KEYWORD

nonn,base


AUTHOR

Antti Karttunen, Oct 31 2019


STATUS

approved



