A030455 Numbers having the same number of digits as letters in their US English spelling.

1000000000, 2000000000, 6000000000, 3000000000000, 7000000000000, 8000000000000, 10000000000001, 10000000000002, 10000000000006, 10000000000010, 11000000000000, 12000000000000, 20000000000000, 30000000000000, 80000000000000, 90000000000000, 3000000000000000

Offset: 1

Author

Dann Toliver, 1999

Keywords

• nonn
• word
• base

Comments

Or, numbers N such that A005589(N)=A055642(N).

Examples

			"One billion" has 10 letters and "1000000000" has 10 digits.
a(7)=10^13+1 (ten trillion one) has 14 digits and also 14 letters in the US English spelling (while the preferred British spelling is "...and one"). The same applies to a(8)=10^13+2, a(9)=10^13+6, a(10)=10^13+10, a(11)=11*10^12, a(12)=12*10^12, a(13)=20*10^12, a(14)=30*10^12, a(15)=80*10^12, a(16)=90*10^12. - _M. F. Hasler_, Feb 13 2012
		

Links

• L. C. Noll, The English name of a number.
• Wiktionary, One hundred one.

Crossrefs

See A204593 for the French version.

Programs

PARI

{N=1; while(1, while(0>d=#Str(N*=10)-A005589(N),);
d | for(k=1,3,print1(k!*N", ")) | next;  for(k=1,90, for(u=0,90, A005589(k*N+u)==#Str(k*N) & print1(k*N+u","))))}

Extensions

Corrected by M. F. Hasler, Feb 13 2012