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A277832 Number of digits '2' in the set of all numbers from 0 to A014824(n) = sum_{i=1..n} i*10^(n-i) = (0, 1, 12, 123, 1234, 12345, ...). 3
0, 0, 2, 27, 389, 5121, 63553, 758985, 8824417, 100589849, 1129355281, 12528120713, 137626886149, 1499725651622, 16231824417465, 174663923187008, 1870096021993551, 19935528121170094, 211700960224046637, 2240466392363923180, 23639231824873799723 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Lars Blomberg, Table of n, a(n) for n = 0..998

FORMULA

a(n) = A277831(n) - 3*10^(n-2) [for n >= 2] = A277833(n) + 4*10^(n-3) [n >= 3].

More generally, for m = 0, ..., 9, let a[m] denote A277830, ..., A277838 and A277849, respectively. Then a[0](n) = a[n](n) = a[m](n) + 1 for all m > n >= 0, and a[m-1](n) = a[m](n) + (m+1)*10^(n-m) for all n >= m > 1.

EXAMPLE

For n=2 are counted the two '2's in { 2, 12 }.

PROG

(PARI) print1(c=N=0); for(n=1, 8, print1(", "c+=sum(k=N+1, N=N*10+n, #select(d->d==2, digits(k)))))

(PARI) A277832(n)=if(n<3, (n==2)*2, A277833(n)+4*10^(n-3)) \\ M. F. Hasler, Nov 02 2016

CROSSREFS

Cf. A277830 - A277838, A277849, A277635, A272525, A083449, A014824.

Sequence in context: A083384 A121971 A278790 * A221674 A240701 A240638

Adjacent sequences:  A277829 A277830 A277831 * A277833 A277834 A277835

KEYWORD

nonn,base

AUTHOR

M. F. Hasler, Nov 01 2016

EXTENSIONS

More terms from Lars Blomberg, Nov 05 2016

STATUS

approved

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Last modified November 17 18:24 EST 2019. Contains 329241 sequences. (Running on oeis4.)