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A276939 Row 2 of A276945: a(n) = A002110(n) + A002110(n+1). 3
3, 8, 36, 240, 2520, 32340, 540540, 10210200, 232792560, 6692786100, 207030183360, 7621298624940, 311671001662020, 13387011595197240, 627972543920161440, 33204048259778536140, 1955349508631402683800, 119211141709561183622340, 7975609932439674026862360, 565799151677779228023294480, 41287621429375723111588738860 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

a(n) = number whose primorial base representation (A049345) begins with digits "11", followed by n zeros: 11, 110, 1100, 11000, 110000, ...

LINKS

Table of n, a(n) for n=0..20.

Index entries for sequences related to primorial base

FORMULA

a(n) = A002110(n) + A002110(n+1).

PROG

(Scheme) (define (A276939 n) (+ (A002110 n) (A002110 (+ 1 n))))

(PARI) a(n) = factorback(primes(n)) + factorback(primes(n+1)); \\ Michel Marcus, Nov 23 2022

CROSSREFS

Row 2 of A276945 (column 2 of A276943).

Cf. A002110, A049345.

Sequence in context: A299329 A020111 A111543 * A188327 A024039 A147523

Adjacent sequences: A276936 A276937 A276938 * A276940 A276941 A276942

KEYWORD

nonn,base

AUTHOR

Antti Karttunen, Sep 24 2016

STATUS

approved

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Last modified February 7 12:25 EST 2023. Contains 360116 sequences. (Running on oeis4.)